The Aplustridae is a taxonomic family of sea snails or bubble snails. The soft parts of animals in this family are brightly colored. The oval bubble-shaped shell is thin and fragile and has a sunken spire. The shell is white or beige-colored with colored bands or stripes. There is no operculum. The soft parts of the animal cannot retract completely into the shell, and therefore these animals depend for their defense on swimming and camouflage. They are specialised feeders, eating cirratulinid polychaete worms.