Biology/Natural History: This species feeds on filamentous algae, diatoms, polychaetes, amphipods, and barnacles (and apparently on sponges). It is common on shaded pilings, where the valves are often overgrown by bryozoans, annelids, barnacles, and hydroids. The reproductive cycle is variable but in California it is mainly from October to March. It does not brood its young. It may have the flatwormNexilis epichitonius symbiotic in its mantle cavity.