Hi Joshua. Suspect your nassarius snail !! I had two which came with my secondhand set-up. Before I suspected them, they had stalked and killed/part eaten my orange spot filefish, pyjama wrasse, flame angel, CLOWNS, and starry blennie. I should have been onto them sooner, but my wife didn't share my suspicion.
These Horrible Creatures are members of the Whelk family, and can move at astonishing speed, and I watched them go everywhere in my tank, ( rough surfaces included.)
Further research showed me that they can hunt and ambush their prey, work in "packs" , and accumulate enough neuro-toxin to be dangerous even to humans. They can stalk from under the sub-strate, and seem to be able to strike in some way ( maybe the eye -on-a-stalk ?) and they take some prey under the gravel and digest them , leaving no trace.
Obviously some "experts" may disagree with me, but I will now follow my own judgement ........ and not pay too much attention to my wife's opinions in the future.
My last clown had been dragged halfway inside the snail's shell ..... QED. ( proof if proof were needed.)
