Margarite Snails (Tegula sp.) are useful members of the cleanup crew. These medium-sized snails have a big appetite, and consume a variety of nuisance algae including hair algae.
They do best at lower temperatures, and like most herbivorous snails these do require the presence of algae and can starve if the tank is too clean. Aside from these requirements, they are hardy snails and a good addition to the reef tank.
Many of these snails are heavily encrusted with pink or purple Coralline Algae like those pictured here, but this varies widely among specimens.