I like Cerith snails. I have had TONS of Nassarius Vibex snails over the years, but look at them more of having a similar feeding pattern to starfish. They will eat stuff that hits the sand, but in the event that they start growing a little or become more aggressive towards feeding, the smaller ones seem to vanish. Cerith snails sift sand A LOT, dig into the sand bed and even feed off of a variety of algae.