Wanted to document this one... it is putting on new shell growth and looking promising, so I am happy but not out of the woods yet. Photo with iPhone under 10k MH unedited.
I got it local. I have only ever seen them for sale at the place where I will not order from again, so I was jacked up to try one not from there. The owner says that they are quite hardy, but they are at 2.5 inches, which helps. I do not know FOR SURE that it is from Cocos (dude was 95% sure that is what his invoice said), but the whole batch of 12-15 looked like it, so I guess that I should say that it is "attributed" to Cocos Island.
No wonder its doing great! Lol. It looks spot on for a cocos. I'm jealous man, can't wait to have some tridacna again. Does your local place ship by chance?