I think ive heard of these before like on freshwater snails, they dig into them or something.. i dk for sure but i wanna just make sure, they're bad from what i hear but i dont know for sure. Its on the side of my clam, it has 2 "mouths" that open and close, it wasnt there last night, heres a pic ( i am probably way off) the one mouth is on the top and the other on the side.

