Balanus nubilus, commonly called the giant acorn barnacle, is the world's largest barnacle, reaching a diameter of and a height of up to , and containing the largest known muscle fibres. Balanus nubilus is a northeast Pacific species that ranges from southern Alaska to Baja California. It is frequently found growing on rocks, pier pilings and hard-shelled animals at depths of up to . Like other acorn barnacles, B. nubilus is a filter feeder; it, in turn, is sometimes eaten by sea otters, sea stars, crabs and the Native Americans of the Pacific Northwest. Abandoned shells of B. nubilus are used by the crab Glebocarcinus oregonensis for shelter. References Barnacles Crustaceans of the eastern Pacific Ocean Crustaceans described in 1854 Taxa named by Charles Darwin