Giant clam shell from Thailand - can I keep it?

[mike]

Do you plan to bring the shell out of Thailand? Then you should check with the customs whether it's prohibited or not. Also with the customs of land you planning to go to. I know for example that in Germany you can bring in 3 pieces of Tridacna clams with you.

And theoretically CITES is about trading with endangered species and as you're clearly not planning to sell it, it probably doesn't apply to your case...