When examining the cases for and against Techeiles, I came across an hour-long video on Radziner vs. Murex Tekhelet: the Truth by Michael Shelomo Bar Ron (MSBR). While the author makes some valid points, I found some holes in it. Here are some of the points in the video and holes. The points I echoed aren’t word for word but sum up what’s being said in each slide. All opinions and responses stated belong solely to the author and to no one else.
I would also like to add that the presenter made a very detailed analysis supporting the cuttlefish Techeiles and, no matter if one wears Techeiles or not, let alone what creature it’s from, we should all strive to respect each other’s opinions.
Warning: this post is long!
Point 1: What we can know about the definition of the murex based on basic dictionary definitions.
The Chilazon of Argaman was a sea-dwelling snail that had a thick, convoluted shell, producing a reddish purple used for Argaman. Belonging to the Argaman family was two types: Argaman and Argamanith (Avraham Even Shoshan Hebrew Dictionary, HaMilon).
a. If we understand Chilazon to be a species of sea creature, it’s either cuttlefish or snail, can’t be both.
b. Also, the cuttlefish has its “shell” inside its body called a cuttlebone, whereas the snail has it outside. As an aside, there’s a Midrash stating that the clothes of Bnei Yisrael in the desert grew on them the same way a Chilazon’s Nartik (shell/bone) grows on it, so there’s that.
c. Also, the Talmud mentions that Techeiles was made from a Chilazon. In Greek, Purpura, while it sounds very similar to purple (hence the misconception), is the source of a range of colors going from orange to blue. It might have been associated with purple since that was the most popular color at the time to dye for royalty. Also, Chazal when translating the Septuagint translated Techeiles as purfira.
d. Playing devils advocate, the majority of Rishonim understand Argaman to mean crimson, as it’s transliterated by numerous sources as Kermes, the forbear to the word crimson. Only through Josephus do we understand that Argaman means purple, which has crimson red embedded with the blue to make a reddish-purple.
Point 2: The Species of Chilazon Itself
a. The Chilazon (Menachos 44a, and Mishneh Torah Hilchos Tzitzis 2:2) is a “dag” which swims, as opposed to a Shablul (snail) or “Sheretz Yam” (teeming sea-creature). Based on this, cuttlefish trumps the murex snail.
b. The Chilazon’s color is that of the sea. It camouflages itself. The cuttlefish camouflages.
c. The Chilazon’s body resembles the sea.
d. One is liable for capturing the snail on Shabbos. The murex doesn’t need to be trapped since it’s a snail.
e. The Mishnah calls a particular hook at the end of a chain a “hilazon-hook” (Mas. Keilim 12:1), which are either long tentacles that are bent-like hooks, or the overall shape of the creature, which is hook-like. The cuttlefish meets this criteria but not the murex snail.
f. The hilazon has a “malbush” (garment) that grows with it (Devarim Rabbah 7:11). The murex only has an assymetrical shell – the cuttlefish wears a prominent “jacket” of sorts.
g. Hilazon-fish rise to to the shore every 7 or 70 years and embed themselves into the sand (Megilla 6a & Chullin 99a). Murex snails never rise to the shore. Due to mass-strandings every 2-3 generations, the cuttlefish does.
h.The Murex population cannot meet the needs of a large Torah public. Dozens of sea snails must die to produce one set of Techeiles. Over-harvesting has already extirpated it from the coast of Israel and Lebanon. Mass demand would drive it extinct within a short time. Over 100 strings can be dyed from a single cuttlefish.
Shablul: This is a land snail , not a sea snail.
Sheretz Yam: teeming sea creature. Tzarich Iyun.
What the text actually reads:
Gemara: Briyaso Domeh LeDag.
i. There’s the halacha of a dag.
ii. The image of the grown murex trunculus shell looks like the profile view of a “hard” standard fish.
iii. “Briyaso” means it’s creation: just like a fish creates by laying eggs, so too does a snail (R’ Avraham Twerski).
Mishneh Torah: Link Here to Chabad.org .
Also: a sheretz yam can also be a Dag, since all sea creatures fall under the Halacha of Dag. See Levush HaAron  (pages 75-78) for more on this. Another great resource is “Tekhelet – Threads of Reason ” by R’ Mois Navon.
b-c. Both the murex snail and cuttlefish camouflage themselves. The difference is that the cuttlefish is like a chameleon in that it camouflages against ANY surface and not specifically the sea. The murex snail is unique in that the untrained eye can’t distinguish it from the seabed, as it looks like a mix of rocks and algae in its habitat.
d. Trapping a creature doesn’t necessarily imply that the creature is fast, simply that the creature is hard to get by ones own hands. By being the color the sea the murex is well camouflaged, and is deep enough that one needs special equipment to get it. The murex is also impossible to gently pick up. Between it being 60-100 feet underwater and barely distinguishable from rocks, you need nets or wicker baskets. See this academic paper on it .
e. A snail consists of a slug which has hook tentacles. Linguistically, Rashi and R’ Gershom both state the old French for Tolaas (worm, spineless-soft creature) is a Limtza. Limece in modern French means slug, and interestingly, in Italian the word for snail is “lumaca.” Furthermore, in Arabic the word “snail” is “halzun,” modern Aramaic has it as “halzona,” and Farsi has it as “Hilazona.” Slugs and snails definitely have tentacles bent like hooks.
Even with the Murex Trunculus, the “tentacle” can be the siphon, based on the murex anatomy seen in the picture below.
f. The “malbush” is moreso a shell then a “skin jacket.” A shell is something that can be discarded, a skin “jacket” cannot.
g. The Talmud states that “it comes up once every 70 years” to justify expense, but doesn’t specify HOW it comes up.
R’ Benzion Halberstam in his video “Glimpse into the Mind of a Posek ” (28-29 mins. in) adds that 70 years and Tekhelet is seen when the Romans had a certain event where a healthy Roman was riding on the shoulders of a crippled Jew (representing Yaakov who limped) and this Jew needed to walk carrying the Roman around. It was meant to symbolize that the Romans were “on top” and the Jews were forever crippled. such that Esav was on top of Yaakov and the Romans were considered “Edom” like Esav was called. This event was meant to be a once-in-a-lifetime event. Once-in-a-lifetime may refer to 70 years because 70 years historically was used to describe the length of ones life. At this event the Chilazon surfaced in much greater numbers in order so that people could more readily sell the blue cloth to others at this event.
R’ Chaim Yisroel Belsky ZT”L explained that this can refer to times when a huge storm can bring a swarm of shells onto the coast.
h. Snails reproduce at an alarming rate, under the right conditions. Regarding land snails :
“When conditions are optimal (warm weather, high humidity), snails can reproduce as frequently as once a month. If the average snail lays 86 eggs per cycle and has an average of five reproductive cycles a year, each individual snail can lay 430 eggs a year.”
While not much information is on whelk/sea snails in reproduction rate, it can be assumed the same with warmer climates. The Mediterranean sea is therefore a perfect breeding ground for them.
- The Chilazon blood is black like ink. Murex dye fluid is greenish yellow.
- One process is to boil the blood. All murex is needed is sunlight and nothing else.
- The Chilazon can cure hemmorhoids. The cuttlefish does (Pliny the Elder, Celsius, and Dioscorides), the murex snail doesn’t.
- Techeiles is Dam Yaruk (spat out) Shel Chilazon. Yaruk identifies it as squid or octopus.
- The Chilazon can remain alive after its dye-fluid is removed as is the aim of its harvesters, so it comes more vivid. Since cuttlefish ink goes out of its ink-sac (not a vital organ), the more vivid and beautiful the techeiles.
- The Sages took great pains to protect their techeiles from laundering, which ruins it. Unprotected murex strings do not fade even with heavy detergent (Menachos 41b, Rabbeinu Gershom Me’ir haGolah). Cuttlefish dyed Techeiles is colorfast but will still fade in the laundry.
- The murex blood goes many shades, starting from yellowish-green to deep dark purple.
2. Not true. When exposed to sunlight for a very long period of time, the water will naturally get to a boiling temperature, albeit at a very long period of time (ever visited Israel?). Also, similar to tea or coffee, you need hot or even warm water in order to best mix the snail-grinds with the water to make the dye. Otherwise, they will remain separated.
3. Based on Dr. Mendel Singer’s piece “Understanding the Criteria for the Chilazon” :
Treatment for hemorrhoids: The Gemara also tells us that the chilazon was used to treat hemorrhoids. Rabbi Herzog states that modern pharmaceutics knows nothing of the use of a mollusk to treat hemorrhoids. Rabbi Herzog’s comments are a bit puzzling. Given that this treatment was from the times of the Gemara, it would be likely
that mention of this would be found now only in non-traditional medical sources, what might be deemed today to be “alternative
medicine”. Additionally, the Radzyner Rebbe had already written that cuttlefish ink has been used as a treatment for hemorrhoids since ancient
times. Indeed, it is still sold today for this purpose. As for murex trunculus, in ancient times it was considered to be bad for the bowels.
Modern and eastern medicine since R’ Herzog, however, confirms the topical treatment of snails, at least with land snails, for hemmorhoids and other skin-related matters. See:
“Topical administration of powdered shells of the land snail Megalobulimus lopesi was evaluated in Wistar rats for their healing activity in an excision wound model… Topical administration caused inflammatory response modulation, crucial to accelerating the healing process, the chronification of which increases the risks of wound contamination by opportunistic pathogens.”
“Snail mucus (or slime, or cream, depending on which translation you read) has been steadily growing in popularity in Korea as a beauty balm for the last few years. In addition to providing a heaping dose of moisture, the stuff is said to cure all manner of ailments from acne to wrinkles to scars.”
Also, from https://www.hindawi.com/journals/ecam/2015/120785/  where it states:
“In Northeast Brazil, macerated shells of Megalobulimus oblongus are an ingredient in folk remedies for asthma, and plasters containing Iphigenia brasiliensis shells are employed to treat gum irritation in children. In the southern region of the country, powdered shells of Megalobulimus lopesi are employed in the treatment of skin burns and hemorrhoids.”
4. Rashi wrote Yarok (yellow-green) or Yaruk (spat out). Without nekudos, this will admittedly always be a source of debate. Yarok works when understanding it being “green” like the sea, a.k.a. aquamarine, and is a reflection of the blue sky based on the scattered sunlight based on the gases and particles in the air. . The sea can take on many shades of blue, similar to the chilazon “blood.”
In addition, the chilazon when alive looks very green.
For more, see:
Levush HaAron 
Yaruk (spat out) also works in that the gland may “spit out” the secretion, but is admittedly not is the best proof.
5. The chilazon when cracked open is still in an alive state, but will naturally die in a short time. Chazal mean that it’s best to extract the dye quickly while the chilazon is still alive as the dye quality will fade away quickly. This matches the murex snail family.
6. I looked at the stated Daf. The daf in question talks about:
a. That the concern about kala ilan has to do with 8-stringed tzitzis and not 4-string, since only two of those strings “have” to be techeiles, and
b. R’ Yehuda gave his tzitzis to a laundryman unconcerned that the techeiles strings would rip, not fade, as it states (https://www.sefaria.org/Menachot.41b.11?lang=bi&with=all&lang2=en ):
רב יהודה מסר ליה לקצרא רב חנינא עביד לה סיסא רבינא חייט להו מיחט
The Gemara relates that Rav Yehuda would give his garments containing ritual fringes to a laundryman and was not concerned that the strings dyed with tekhelet might become detached and that the laundryman would replace them with strings dyed with indigo. Rav Ḥanina would form a bundle with his ritual fringes so that they would not become detached while they were being laundered. Ravina would tuck them into a pocket he formed on the garment and sew the cover of the pocket in order to protect the ritual fringes.
The key term though is Mareh HaTecheiles, Mareh, appearance, out of context is vague. It can mean the color disappearing or that the appearance gets damaged because when the strings detach, there’s no Techeiles on it, or at least enough length to fulfill the mitzvah.
In general, the idea in that it’s both steadfast AND fades quickly sounds like an oxymoron.https://s3.amazonaws.com/mywesternwallnet/wp-content/uploads/2019/05/24034231/menachos-41-dafyomi-r-aryeh-lebowitz-907436.mp3 
- Murex was always known as the source of argaman (red/purple). The sages never argued that murex could be used for both. Why didn’t professional dyers see the connection between their industry and the mitzva? Simple: Tyrian purple is not techeiles.
- The sages teach how fake techeiles was produced from the indigo plant kala ilan. Prussian blue can be dyed to match indigo.
- Murex was known as the source of purple as that was royalty, but the “purpura schneck” was used for a range of colors, from orange to purple, with blue included. Goyishe dyers didn’t see the connection because they were goyim, and the mitzvah didn’t apply to them. Jewish dyers made blue and techeiles based on if it was Lishma or not. Tyrian purple isn’t techeiles: that’s why sammamanim (salts/spices) were added. Otherwise there would be a problem with reddish-purple strings.
- Beautiful. Problem is that the source of blue is from the iron filings and not the squid fish itself.
Point 5: Ingredients
- Ingredients of Radzyner Tekheleth: Potassium (Ashlag – Potash), Sulfuric Acid (Borit), Ammonia (Mei Raglaim – Urine).
- Could ancient ovens reach 900 C? Even hotter: Remains in biblical Timna from 12-13 centuries BCE show that ovens could produce temperatures even hotter than 1200 C!
- Iron filings: Iron was derived from the oxidized meta of the vessel itself. Stainless steel doesn’t give the free iron, so iron filings are needed to substitute.
- Sammanim mean salts or spices, so it’s pretty vague and open to interpretation there. Interestingly the Mei Raglaim-Ammonia-urine was used AS the test, rather than an essential ingredient. It was only removed once proven to be so caustic that, even if the Techeiles was kosher, it would be destroyed by the mixture.
- Hot ovens in Timna? Sababa. Doesn’t mean conclusively that it was used for Techeiles. I guess the Radzyner stance is that the absence of evidence isn’t the evidence of absence.
- That’s a bit of a strain. Since all dyehouses were destroyed, we have no evidence which pots were used. For all we know it could have been earthenware vessels which wouldn’t have released the iron secretion. Besides, the source of blue still needs to come from the sea creature itself.
Point 6: Chemical Tests
- Techeiles test: straw, slime slug, and urine left to ferment for 40 days. Radzyner techeiles meets that requirement.
- Okay. So does murex.
Point 7: Why this creature was designated as the only creature for Techeiles
(straight from Tosefta, Menachos 9:6)
- The form of the Chilazon declares its purpose and its Creator. With 8 arms and a colored stripe, it resembles a tassel of Tzitzis. It’s color-camouflage indicates that the Tzitzis must match the color of the beged.
- It flees its predators by creating a dark cloud between itself and them, enabling it to escape through the sea. This is similar to Bnei Yisrael escaping the predatory Egyptians in the Yam Suf.
- Techeiles is supposed to enable one to not stray after their eyes. The cuttlefish has the most acute polarization of vision found in any animal. Also, after mating and the female lays her eggs, both male and female cuttlefish die, similar to the Sotah case.
- Cool. Regarding Sotah, I didn’t know that sea creatures weren’t forbidden from mating with each other and Hashem’s name was erased in water.
- For the murex trunculus, it can be argued that the shape of it resembles the shape of a fish, which is Dag. Additionally, “Dag” which is 4+3=7 works with Shabbat which is also central to all other mitzvos, relating specifically to the traditional food. Challah is Gematria 43. 4+3=7. Soup (Marak) is Gematria 340, 3+4+0=7. Basar (meat) is Gematria 502, 5+0+2=7.
Bottom-line, Gematrias and hints are not meakev (crucial) to the validity of one sea creature over another.
Point 8: Debunking Murex and Cuttlefish Myths
- “With Radzyner, you can dye ox blood, or Gefilte fish blue. The blood is no importance to the color.” So? That’s imaginary. Rambam only states that boiling with Sammamanim – chemical additives – changes it from black to blue. Since when did Chazal care about the fish’s chemical contribution?
- “What about the ancient Techeiles dying factory in Israel?” What dying factory? These piles of murex shells are also found in Tyre and Sidon in Lebanon, and are the remains of the dying factories used for Argaman.
- “How can you even talk about the Radzyner Techeiles after the discovery of the Bar Kokhba cave? They were dyed with murex Techeiles!” Those weren’t on strings, they were on a garment which clearly proves they were used for decorative purposes.
- “Isn’t the murex shell proof that this is the Chilazon?” Dr. Norman Lamm told Baruch Sterman that the Bar Kokhba coin was proof of this being used for a mitzvah. Dr. Mendel Singer claims that he referred to a Tyrian coin, not a Bar Kokhba coin.
- “Radziner Techeiles bleeds and comes off in the laundry, meaning that it can’t work.” That’s a proof that it is it. The dye bleeds with some strings but not all. Murex Techeiles not bleeding is a strike against it. And Radzyner methods are getting better to become stronger and more colorfast. It’s a work in progress.
- Rabbi Herzog said that those looking for the murex are in for a big surprise. He then suggests the Janthina. He actually would be angry for the murex proponents for distorting what he said.
- “How can you not be ‘wowed’ by the 613 nanometers discovery by J. Wouters and A. Verhecken on the Techeiles molecule?” That’s dubious, and has no standing in the Torah.
- “Kala Ilan was used for fraudulent Techeiles. Murex dye can be done to look similar to Kala Ilan while Radzyner is Prussian Blue.” Radzyner Techeiles looks the same as Murex Techeiles.
- If this is the case, then Techeiles wouldn’t be so expensive as the source of fish shouldn’t matter. Chazal didn’t only state it needed to be from a Chilazon for a mystical reason, but for a practical reason as well. Playing devil’s advocate, while there might have been a magical dying method for cuttlefish Techeiles that’s not documented and is more expensive, why didn’t Chazal prohibit that fish as well and not only Kala Ilan? The likeliest answer is that the murex dye was the one used for all kinds of dyes, including Techeiles.
- Dying factories were used to make all kinds of colors, not just purple. Bugs were used for tolaas shani but there are no bones remaining for that. One might argue the same with the cuttlefish, but then you would see tons of cuttlebones. The cuttlebone isn’t made of cartilege, but rather a “a hard, brittle internal structure (an internal shell)  found in all members of the family  Sepiidae. ” Also, there are fossilized cuttlebones, so the archeological question still isn’t dismissed. As per counterpoint 1, expense was a huge concern and therefore a “red flag” if Techeiles can be sold for cheap.
- Great. So why wasn’t the decorative blue added on top of the Kala Ilan dye by the Chachamim that it couldn’t be used? It wasn’t practical? What about the cuttlefish dye which, mentioned earlier, could produce ink dye more easily? After all, “over 100 strings can be dyed from a single cuttlefish.”
- Good point, no argument here that this isn’t conclusive evidence of it being used exclusively for Techeiles. However, the fact that this was a huge commercial dye for all sorts of colors including Techeiles is difficult to ignore.
- This is a self-contradiction. If it’s meant to bleed, what’s the point of the Radzyner method working to be more colorfast? Doesn’t that deligitimize the Radzyner Techeiles by that logic? The fact is that it needs to stay colorfast, and also, the fact that fabrics with murex dye from 2,000 years were found is proof that it could withstand everything, especially during the rainy seasons. The cuttlefish ink-dye still leaves a filmy residue and blue lines which, the Radzyner Chassidim can continue to work on ’til kingdom come, will not change as squid-based ink can never be “steadfast.” Also, the blue is Prussian and synthetic, and only can latch onto the ink under enormously high temperatures. One can learn from this that the fire of Chassidus can effect anything. Still, it’s not directly from the cuttlefish and presents a problem. Regarding this being the way it was done in ancient times, that’s hard to say definitively if iron ovens were used for this purpose 2k years ago.
- Rabbi Herzog suggested the Janthina sort of as a joke AFTER trying out the murex trunculus. He acknowledged that the problem with the Janthina was that it turned brown very fast. He loved the murex trunculus and this was the basis of his doctoral thesis on porphyrology. He supposedly was able to get the color blue once but wasn’t able to replicate those results in cloudy Leeds, England, where in addition most tests were done indoors. As the saying goes, he was right the first time around.
- Agreed. However, that’s a “side swipe” and doesn’t prove or disprove anything. In addition, the “techeiles” spectrum is in the six hundred teens, not specifically 613. Also, the number 613 Mitzvos in itself is actually a Machlokes. For example, does Tzitzis count as 5 mitzvos or 1? Does Tefillin (shel rosh and shel yad) count as 2 mitzvos or 1? Etc. It’s a cute reference though.
- The finish though is a bit different, and I’ve personally seen Radzyner dyed techeiles completely faded after some washes from the dry cleaners. Also, under the microscope is where the difference really lies. Murex techeiles is chemically exact to kala ilan while Radzyner isn’t. And, to say that that disproves murex Techeiles, why didn’t Chazal warn against the murex schneck?
As long as you’re happy, I’m happy.
As a final aside, the idea that it can survive on land for a while would work with the overall snail species, but would be ridiculous to assume the same with the cuttlefish.
Above all the above points, my personal criteria is in knowing that there plenty of Rabbis WHOSE NAMES I RECOGNIZE wearing tekhelet of one of the creatures. It turns out that there are quite a few in favor of the murex: https://www.mywesternwall.net/2017/11/03/top-32-rabbis-and-founders-wearing-tekhelet-techeiles.html 
Video Author: Rabbi Michael Shelomo Bar-Ron
Author Website: http://www.torathmoshe.com/
Facebook Page: https://www.facebook.com/michaelshelomo.barron
Bio from Facebook Profile: “Rabbi or “Mori” Michael-Shelomo Bar-Ron is a publishing Torah scholar. He is both a communicator of science to Torah-observant Jews and Noahides, and a communicator of rational Torah to secular audiences. He is a life-long student of Torah and science, particularly biological anthropology, biblical archaeology, and environmental science.
Due to the widespread attention Mori Bar-Ron’s last four academic papers have received, he is currently a top-1% contributor toAcademia.com.  His books, Guide For the Noahide (Lightcatcher Books ©2009,2010), Oral Torah From Sinai (Lightcatcher Books ©2011), and Song of the Creator (Lightcatcher Books ©2015) have been hailed by rabbis and lay readers, Jews and non-Jews from around the globe, for elucidating in layman’s terms the rational genius, deep antiquity, and breathtaking structure of the Oral and Written Torah. His lecture tours, based on his work, have enthralled audiences in the U.S. and Europe. He has been interviewed on Cable TV and Arutz Sheva radio shows, and his writing published on their website.
Rabbi Bar-Ron has a BA in Biological Anthropology with a Minor in Judaic Studies from U.C. San Diego. His academic studies brought him to the Hebrew University on Mount Scopus and Yeshivah University in New York. His ensuing Torah journey brought him from Yeshivas Ohr Sameach to rabbinical training at Shehebar Sephardic Center in Jerusalem and years of tutelage under rabbis and scholars of Sephardic and Yemenite Maimonidean tradition.
Throughout his Torah education, “Mori” Bar-Ron’s love for genuine science (and disdain for pseudoscience commonly embraced in religious circles) has never waned. After years of maintaining a critical, balanced mindset as an understudy of scholars with opposing outlooks, he found compelling answers and rational solutions to controversies that have helped many return to and maintain their Torah observance. He maintains a growing virtual Beit Midrash of some eighty active students worldwide and a subscriber base of nearly 1,000. Recently, the focus of his research and teaching has shifted back to academia. His new translations of Proto-Sinaitic inscriptions in the Sinai Desert reveal them to be priceless relics from the Exodus. His examination of a cylinder seal impression found at Tell ed-Daba strengthen the historicity of the biblical Joseph and several details in Genesis.
Living with his wife and children in Israel for 19 years, his home and Torah center, Beit Midrash Ohel Moshe (www.torathmoshe.com ), are in Beit Shemesh. Rabbi Michael-Shelomo makes a living as an English professor in Jerusalem.”