I too had 2 rock crabs that made bee-lines for fresh meat. I trapped them and tossed him out in the frozen sidewalk, what an unique find for kids on their way to school, I also had one of those proboscis snails (the kind that bores through tridacnids?) who also made bee-lines for the fresh meat, tossed him out too.
100 gal tank with sump, no substrate, all water is RO, Alk is a little low, Ca 350, ph 8.3, phosphate0, nitrate 0, salinity is down to 1.15 due to emergency top offs following some major skimmer overflows, lighting 2x150W MH/2x48 actinic flourescents, live rock~100#,(6+ years in the tank).
1 blood shrimp inhabitant and some snails and crabs (previous neglect followed by 400km move had all the fishies crab food)
I am dripping Kalk regularly i.e. 1 litre/2 days, adding TectraCB, and have prepared some 1.35 salinity water to drip in to bring salinity back to 1.25. 0 mortality with hermits, they have actually outgrown their first homes and moved into Turbo shells. this wouldn't be so bad except Turbos and hermits are expensive only to die (usually hidden somewhere) and load the water before I can find them. no evidence of slime on the dead finds but lots of opercula, probably pried off by the hermits, there is plenty of caulerpa and other algaes for the turbos to munch, brown hair algae is present, bryopsis, enteromorpha.