Cup-and-Saucer Shells and Slipper Limpet of the Calyptraeidae Family are gastropods mollusks. The shells may be circular, elliptical or oval in profile that may have a centered or marginal apex. The exterior sculpting may consist of radiating, spiral and wavy ridges, fine bumps, or small spines. The interior of the shell is smooth. All individuals in the Calyptraeidae Family start life as males and transition into females later in life. Some species form “mating stacks”, where multiple males stack on top of one female. When the female dies, the bottom male becomes a female.

These Shells are found on hard substrate, often times on top of other sea shells, intertidally to depths up to 200 m (655 feet). They are generally sedentary which allows their base to conform to the shape of the surface on which they reside. Calyptraeidae Shells are suspension feeders, using mucous strands to capture plankton and detritus from the water column. In turn they are preyed upon by crabs, predatory mollusks and sea stars. These shells are found in tropical, temperate, and polar seas. There are one hundred thirty-five known species in the Calyptraeidae Family of which nineteen are found in coastal waters along the Baja Peninsula.