Common name: Worm Snail

These immobile snails have the appearance of feather dusters without the feathery crown. Instead, there are two short antennae coming out of the tube opening. Vermetid snails send out a mucus net resembling a spider web (seen in the picture), which traps planktonic material, then they reel it in and feed. The calcareous tube it forms projects it out into the water column. Generally, these are harmless filter feeders, but sometimes can get on tank equipment. If they seem especially bothersome, then good nutrient control may be in order.