[caitrina]

are you sure it killed the snail? Did you see it kill the snail? Perhaps the snail had fallen and was unable to right itself at some point and died and little hermie came along and protected your system from ammonia by devouring the snail and then taking its shell. That could be a thought, unless of course you saw it stomping through the rock with knife and fork in hand, pummeling the poor defenseless stupid snail.....sorry you lost a snail....