Does anyone know what this is?

[Tohni]

I flipped over a rock in my refugium and found which looks like a oyster or regular saltwater clam attached to a rock. It is alive. I have noticed it opens a little, when I touch the rock it will close. Doesn't really look like a regular saltwater oyster to me but I don't think saltwater clams adhere to rocks??

 

[Fudsey]

Bivalve

 

[cracker]

Could be a jewel box clam? Any live rock from the sea lately?

 

[Tohni]

Could be a jewel box clam? Any live rock from the sea lately?

No, some conch shells from the sea. I always boil them before putting in the tank though. I've never heard of a Jewel box clam.