The OU sourcebook shows that the murex trunculus techeles are NOT clearly the right ones. Too many kashyes:
1. The dye is chemically indistinguishable from kala ilan (indigo). Yet, the gemara says there was a test to distinguish techeiles from indigo.
2. The murex trunculus shells are not the color of the sea.
3. Murex trunculus doe not come up every 70 years.
There were a slew of other kashyas which I don’t remember offhand. But the bottom line is, it’s not a slam dunk by any stretch of the imagination. Tishbi yetareitz.