I had a majano anemone on one of my rocks, so I removed the rock and stuck it in freshwater for a few days while I was on vacation. I assume the anemone is dead, but I returned to find that the rock was in fact a clam! I have no idea what kind of clam it is, but it never had a fleshy mantle.
Few questions: is the clam likely dead? How could I tell? Could I return this to my tank, or will it pollute? Otherwise, what should I do with it (dead or alive)?