Your research and work is absolutely fascinating! It’s nice to see this ancient craft come back to life. I’m not convinced though that the murex is the creature that best fits the descriptions. Have you considered checking the heteropod family (carinaria, pterosoma, etc)? They are sea snails with only part of their body covered with a shell. The color of their bodies is like the sea in that they are mostly clear (transparent). Like nearly all gastropods they have blue blood. Of course that doesn’t point to any particular heteropod! They are quite often pisciform (shape of a fish) with their fin and the way they swim. Just a thought! Keep up the good work.
Blue blood – does not necessarily make for a blue dye. There are many animals that have blue blood – as you mentioned – from lobsters to Octopus. Tekhelet has the unique property of dyeing fast onto wool – and that is a very rare property. Actually in the Murex snails, the dye (dibromoindigo) comes from the digestive system and is a result of two strange properties of the Muricae. First that they are meat eaters, thereby producing indole as a byproduct. Secondly, they choose to neutralize the poisonous indole using bromine instead of chlorine which would be the natural choice, since it is 60 times more abundant in sea water. Remember that the Tekhelet/argamman dyeing industry was the most important economic industry in the ancient Mediterranean. That means that we should know about it from historical records. Assuming that the Jewish tekhelet was the same as the blue dyed by the rest of the world, then the historical records we can search are much broader than just the Talmud and Midrash. I think that I can justify that assumption for a number of reasons. One obvious thing that points to the fact that tekhelet was identical for the Jews and the rest of the world is that the word itself actually predates the Bible. Also, Mordechai in Persia wears tekhelet robes when he is appointed to the premiership. So, what do the other sources say? Pliny, Aristotle and Vitruvius all write about the snails used in dyeing and those descriptions clearly point at the Murex. Archeological evidence is absolutely clear that Murex were used in a very extensive dye industry for thousands of years from Israel and Lebanon to Crete, Greece and Italy. I don’t know if this proves that there couldn’t have been another snail used, but if there was, then I would look for some record of its use. – Baruch Sterman