geez you guys make mantis seem like the baddest thing in the ocean. there are several aggressive fish that will bite these things in half if given the chance. Puffers, Triggers, many large wrasse. Of course they can kick a hermit, snail or chromis butt, what cant. Dare I say most of your fish arent in danger unless you have small fish. I would be pissed about the cleaner shrimps (it could eat all the peppermint, snails and crabs it wanted).
Pain to get out huh, this is exactly why I pick up, spray off and inspect EACH rock one by one before putting it in the tank. (but now that you guys got me worried about getting clubbed or speared I will purchase some large tonques for this exercise in the future).