Crepidula plana, common name the eastern white slippersnail, is a species of sea snail, a marine gastropod mollusk in the family Calyptraeidae, the slipper snails or slipper limpets, cup-and-saucer snails, and hat snails. This species is characterized by a flat white shell, a white body and development that includes a planktotrophic larval stage. This species often occurs inside large gastropod shells that are inhabited by hermit crabs. Due to this habit the shells are often very flat or even recurved.