HollyMoe: Your “proof” can be easily rejected.
If they found “hundreds of millions” of trunculus shells they obviously were not rare enough to even fit a “figurative” interpretation of the Gemara that they only surface every 70 years. Furthermore equating kala ilan with indigo is pure speculation. Additionally, the trunculus extract is NOT naturally blue, it is RED. Only after exposure to numerous chemicals and extended sunlight does it turn blue, and this is NOT mentioned in the (halacha not aggadata) Gemara that describes the process of producing techeiles.