Emerald crabs are 50/50, some eat coral and some dont. One of mine at 3 frags of whammin watermelon zoas before i saw him at night chosing down on so magician zoas. Caribbean porcelian crabs are awesome, ive never had one eat any corals and they filter feed. The perfectly reef safe crab. Dwarf zebra hermits are reef safe and cool ive got 20 in my 37g and 10 in my 20, no problems yet after 4 months.
One of my dwarf zebra hermits
One of my caribbean porcelain crabs
Some snails are:
Nassarius,banded trochus, margarita,nerite,asteria, and much more. Those are just the ones ive kept so far.