WHAT is this???

[sopkot]

Please tell me what this is on/in my rock? Opens only slightly and closes if anything gets too close to it.

 

[franciscosalazar]

Clam?

 

[sopkot]

Maybe, but most clams I see are bright and beautiful inside. Plus they are much more open. This looks like the clams I eat.

 

[Scribe]

I'd have to say it looks kind of like a clam to, but hard to tell for sure. I've had tons of clams show up in my tank. It could be like one you eat. Not every clam is a big, fancy and brightly colored.

 

[unchin]

Could be some sort of barnacle. How large is it?