Halakhah su Deuteronomio 33:19

And as for what is mentioned in the Sifre (Deuteronomy chapter 354) concerning the verse "'For they shall suck of the abundance of the seas' (Deuteronomy 33:19) Said Reb Yose: One day as I was traveling from Keziv to Tzur I encountered an old man, and greeted him with 'Peace'. I asked him 'what is your means of livelihood?' He told me 'the Hillazon'. I asked him, 'can it be found?' He told me ' By the Heavens, there is a place by the sea, situated among the mountains, and poisonous insects bite it (ie. the Hillazon) and it dies and it rots in its place.' I said to him 'The Heavens are a remembrance hidden for the Righteous for the world to come.' 'The treasure'; this is the Hillazon," etc, see there. From this it may be implied that the Hillazon from which the Techelet dye was made, was hidden. However, indeed that would be questionable, for during the time of the 'Tanaim' (1st-3rd century CE) one must have been able to acquire the Techelet since we find Techelet in use even in the days of the 'Amoriam' (3rd-6th century CE), as is mentioned in tractate Menachot (42b) "Abaye said to Rav Shmuel bar Reb Yehudah, this Techelet, how do you dye it?", see there.

The fourth objection: Why should one search in vain for the Hillazon without benefit for even if we would attain this way Hillazon that the Sages of blessed memory intended and we could recognize it according to its signs that is with all certainty the correct Hillazon we still would not be able to use its blood to dye the Techelet, because the Sages of blessed memory have already said in Tractate Megillah (6a) that everyone needs you (Zevulun) because of the chilazon. Judges (5) What is the reason because Naftali received as their portion in the land of Israel the high places of the fields. Zevulun said before G-d, Master of the Universe you have given unto my brother the fields and the vineyards and unto me you have given mountain valleys. To my brother you have given him lands and unto me you have given the seas and the rivers. G-d answered him saying, Because of the Hillazon everyone needs you as it is said in Devarim(33). The nations will call upon the mountains and the hidden treasures of the sand. Rav Yosef taught the "hidden is the Hillazon and the treasures are clear glass (crystal). Zevulun said before G-d 'Who will make it known to me that this is true. Hashem answered him and said There they will offer their righteous sacrifices (ibid). This will be your sign 'Whom takes from you without payment will not be successful in his business - and Rashi explains that if he takes the amount of Hillazon which is worth a Prutah (a small coin) without renumeration for it the color will be ruined and will not be of any benefit at all, Therefore even if we could attain the proper Hillazon we would be taking it without paying for it to the tribe of Zevulun for we have been exiled from our land and Zevulun is not in their inherited place that we are able to pay them therefore the color will be of no benefit and why should we toil in vain. Therefore even if it seems to us (to the naked eye) that we would be able to dye with its blood the color of Techelet we must be forced to say that we are mistaken for certainly the words of our Sages of Blessed memory are alive and everlasting.

8. It has been explained already that the Hillazon emerges from the sea to the mountains. And it is written in the holy book before Hakaneh in the laws of Tzizith, that immediately upon emerging it is entrenched in the earth and there it procreates. And he concludes by saying that it is rooted there and its head is outside. It can be understood from this that it is the way of the Hillazon to dig and to bury itself in the earth. Rashi in Tractate Megillah (6A) who wants us to understand each word the Talmud explains according to the order of the words in the passage explains the word S'funei as importance rather than buried which fits in both according to the simple meaning of the passage.