Distinguished from true limpets by the breathing hole or slit on top of the shell. Oxygenated water enters under the edge of the shell near the head and passes over large paired gills, then out through the slit along with with waste products.

The family is usually found on or under rocks in the lower intertidal zone, and deeper waters. Most feed on plants and debris, but some prey on sponges, foraminifera, and diatoms.

An old, eroded shell of an Elephant Snail, Scutus antipodes