In the Gemara in Maseches Sanhedrin, daf 91a there’s a very interesting thing we can learn about the sugya of techeiles. As to why P’sil Techeiles, so far as I recall, does not have this in the document with all the proofs for murex techeiles they have on the site, I have no idea.
There Chazal bring several different mosholim (parables), and in one of them a person is told to go to a mountain; on that mountain there is only one Chilazon today, but when it pours rain, there will be loads of Chilazonos. What is a Chilazon? Says Rashi, the Chilazon is a tol’as (invertebrate bug creature, warm/slug/snail) that is used to dye the techeiles color. So what creature comes out when it rains? Anyone who has lived in a place with snails and rain knows that slugs and snails, along with worms, come out in droves in the rain. In the Gemoro in Menachos it describes the Chilazon, this same techeiles dying creature, as being like a fish, meaning sea-dwelling creature in the language of Chazal, dwelling in and around the sea. It’s painfully obvious, considering what we know now, that the murex trunculus is the techeiles snail. At least where I’m from (Pacific NW), you can quite often find sea-snails crawling around on land so long as it’s wet nearby, and it could easily be assumed that the murex is no different in this regard.
That is not to say that those who wear the Radziner/cuttlefish techeiles are wrong in their practice. They have whom to rely on and there are plenty of shittos that say that so long as the dye comes from a sea-creature it is still kosher. For those who have been on the fence though, I hope this helps in your decision making process as to whether to choose to fulfill the mitzva of tzitzis in completion with wearing techeiles made with the truest known Chilazon, the murex trunculus snail.
Yismach Lev 