Eastern White Slipper Shell
Crepidula plana Say, 1822
Eastern White Slipper Shells are generally less “humped” than the Common Atlantic Slipper Shell. In fact, Crepidula plana may be rather flat, convex, or even concave. The apex usually is not turned to one side.
The shells are white and, of course, have the characteristic platform on the underside. This platform, or partition, protects the gastropod's soft organs. There is no operculum (the calcareous or corneous structure attached to the gastropod's foot, used as a door to close the shell's opening or aperture). Eastern White Slipper Shells seldom grow larger than one and a half inches in length. Their exterior surface may be either smooth or marked with concentric growth lines.
The Eastern White Slipper Shell attaches itself to solid objects — other slipper shells; most dead shells of the same type which hermit crabs choose to occupy, whelks, moon shells; and other solid objects. Frequently a horseshoe crab will have several dozen Crepidula plana on the underside of its domed shell. The Slipper Shell is not permanently attached to these surfaces, but rather uses its foot to create suction for holding onto the object. It may remain “stuck” for long periods or even until death. Rarely does Crepidula phana “pile up” in stacks like Crepidula fornicata.
Eastern White Slipper Shells can be found on beaches from Nova Scotia to Brazil, and on the shores of Bermuda. The living gastropod inhabits shallow waters.