I was serious about the goby, but it wasn't dumping sand into the clam, it is a really small goby so only a tiny bit of sand, but I'm pretty sure some got in. Who knows since I'm not able to watch the tank all the time. I'd already moved the clam prior to posting so the sand problem is gone, but it may have already done too much damage. Is there anything else I can do? Can the clam somehow force out the sand? Thanks for your help.