I have various snails, but just added the following: (all quotes from ipsf.com).
Nerite Grazers tm (Nerita sp.). Exceptionally hardy herbivorous snails; superior glass polishers; jet-black in color, night feeders.
Strombus Grazers tm (Strombus maculatus). The marine aquarium industry's hottest new grazer. Reef-safe, highly active, approx. 1/4 inch shell. These are miniature Pacific relatives of the famous Queen Conch known from Caribbean waters. Hawaiian Strombus Grazers stay small and never exceed about 1/2 inch in length. They are the perfect size for reef aquariums!
MicroHermits tm (Calcinus sp.). Reef-safe, highly active, approx.1/4 inch shell. Great rock and sand cleaners. Add to sand at bottom of tank after acclimation. These small hermits pose no threat to the snails in your reef aquarium.