Whats wrong with my Clams?

[tim the toolman]

Keeping in mind the death of the moorish idol could it also be possible that the idol was eating a nuisance critter that is no longer being controlled in the tank? I know they thrive primarily on sponges and such, but in the wild they are also well known for eating benthic invertibrates which is a rather large spectrum of invertebrates including some which live in home aquaria. (Just a thought)