There was a company called Red Bear Trading Co. which had some sort of protein that was very similar to sea turtle carapace (it was NOT exact, but "in the ballpark"). I think they grew the stuff in a petri dish or something.
It made for pretty good picks. They were about $25 a pop. You'd have to sand them sometimes and it smelled really bad. I used to use them, but then their wait list got SO long (months) due to each one being made by hand. They should've just charged more.
I finally went back to celluloid Fender mediums out of frustration because it just wasn't worth the hassle. I sound like me no matter what, and it just was not a reliable/sustainable solution for me, given how if I lost one it would take months to get another. The string company I endorse sells celluloid picks that are much like Fender mediums, and I just have them send me boxes of those, and I just get on with it.
But I would love a real, antique turtle shell pick one day.
They used to make combs and hair barrettes out of sea turtle shell because it has a unique property-- it's anti-static. It WILL not build up static electricity. Maybe if someone found a stash of old hair accessories, there would be enough material to make picks out of...