Over the last month I added a few clams to my tank. I think both are Maximas. One is purple, one is blue. Today, I came home to find the purple one missing. Let me clarify, it's not missing, the shell is there, but it's licked clean.

I have two hypothesis:

1) Something got hungry and found a snack.
2) He was on the decline and something got hungry.

Both clams have been open and seemingly happen since I got them. They are in the sand. Blue maxima is still there as happy as can be.

The only two things in this tank I could think would go after the clam are my red reef crab or my cleaner shrimp. I've seen the shrimp rip the guts out of a dead turbo before so I don't think he'd have a problem doing the same to the clam. I've also seen my emerald mess with my other clam, but he's in the sump now due to that incident. I only have the small reef crab. No other hermits or snails.

Fish are: Occy, Flame, Kole tang, royal gramma, lawnmower blenny, and a green mandarin.

So, what do you think happened?