Bit late but for reference but here goes
Trochus, Cerith, money cowry snails,
Tuxedo, orange-spined & purple-tipped urchins,
Cerith, Nassarius, bumble bee, strawberry conch & fighting conch snails,
brittle stars (but not the green ones, which grow huge & eat fish).
Rocks & sand:
True blue leg hermits (too small to harm most snails) NOT electric blue-knuckled hermits which get too big & can kill snails.