Well, my O scyllarus (Peacock) seems to dislike the taste of one type of snail, so I keep 3 or 4 of them in there to clean. he will frequently spin them around,peering,then toss them away. My G. viridis shows no interest in eating hermits (Some have been in there nearly a year...).
So, it is possible to find a clean-up crew in odd instances...
As far as 'Reef Safe' with your corals goes:
I collect all of the little loose mushrooms, rocks with one or two polys etc...from a LFS (For free,even!) and drop them in my 'Orphan's Home' in my G. tern's tank. I put in a piece with 5 brilliantly colored zoos...which she promptly hid somewhere.
:|
The poor things will probably die now,since they aren't anywhere wit light, then they will pollute the (12 gallon) tank,causing spikes...
She also tears up caulerpa frequently and rearanges it on a weekly basis.
Mantis move things (rocks,LR etc...) around a lot, so any small pieces of coral fauna are at risk. If your corals are secured on large peices of rock, there should be no problems.
-Ron