Bought a reef pack from Saltwaterfish.com and it came with 2 cleaner clams. 1 is missing so I'm assuming it is under the sand somewhere and when I got home from work today the other ones shell is WIDE open. I believe something ate it?? I have 2 clowns, 1 blue hippo, 1 yellow tang, 1 carpenter wrasse and 1 sand sifting goby. along with 2 pep shrimp, 1 coral branded shrimp, tons of hermits, sally lightfoot and 5 emeralds. What do you thing too the clam out??