Identification?

[TheLandShark]

Can anybody identify these clams they are alive and I’ve had them for about a year. They came in on a Zoa colony. Will they get bigger and turn out to be kool or anything? They are small enough my copper and can’t get inside them lol

 

[ISpeakForTheSeas]

Pics under white light from a variety of angles (including ones that show the mouth and hinge if possible) would help with an ID - that said, from the pic provided, maybe a mussel species?

Either way, I wouldn't expect them to get too much bigger.