Snail graveyard; possible mantis

[G1GY]

I have a bullseye pistol shrimp that does the same thing. I'm not so sure that a mantis will keep it so organized back there, but I know for a fact that a pistol will keep a nice neat pile. Also, My pistol just walks right up to the snail and just carries it back to it's home for dinner and then eats it without damaging the shells. I've also watched it kill hitchhiker crabs after I've injured them.

Hope this helps.