Biology/Natural History: The plates of this species may be heavily eroded by the boring sponge Cliona. Often grow on one another, forming clusters (druses). Barnacles are hermaphroditic, and fertilization is internal. They brood their eggs for several weeks before releasing them as nauplii. The nauplius molts to a cypris, which feeds in the plankton then settles and metamorphoses into an adult. Predators of this species include Pisaster ochraceous. The empty shells are refuges for Cancer oregonensis and Octopus rubescens. This species contains very large muscle fibers which have been used in the study of muscles.