Rough limpets sport bowl-shaped, heavily ribbed shells in brown or gray. Over time, using the scalloped edge of its shell, a rough limpet grinds a groove in a rock until the shell fits perfectly. These custom-made “homesites” are covered by water only during spring tides and/or when the surf is high. At other times, spray from strong waves reaches the limpets, but doesn’t cover them.
When the rocks are wet, limpets move about, grazing on diatoms (microscopic plants) layered on the rocky surfaces. When the rocks are dry, limpets must take action to conserve moisture. They return to their homesites, where they snuggle in by clinging tightly with their muscular feet.