So I've taken a liking to these lil snails called Nerite Snails. They're also sometimes called Tapestry Snails. They're an intertidal snail from the Pacific and the Carribean Oceans. They stay small and they get to be about half an inch long at the most. They eat small/basic algae. I've seen them in a handful of stores. I've bought some from Aquarium Concepts and Cali Reef Co. Haven't seen to many at the other LFSs, probably because they don't perform as well (algae-eating) as the standard Trochus/Turbo/Astrea combo. They are intertidal so they may take a little stroll outside of your tank. I haven't had these happen in my or Jill's tanks but our tanks have a rim so they have to put in a little extra effort to escape. We don't have lids. I particularly like them because of the variety of colors they come in. Just one more thing to spice up the invertebrate diversity of a reef tank. Great for those tired of just seeing the trochus/turbo combination. I've notice you need to acclimate them slowly or they don't do well. Mine move slow at the initial introduction to the tank and then become acclimated to tank parameters. The ones in Jill's tank move super fast compared to the ones I just introduced to my tank.