Barnacle

       Barnacle is the name of a family of marine crustaceans, or water-breathing animals, having a crust-like shell or scab enclosing them. This mantle or shell is composed of five principal valves and several smaller pieces, joined together by a membrane attached to their circumference; and they are furnished with a long, flexible, fleshy stalk, provided with muscles, by which they attach themselves to ships' bottoms, submerged timber, rocks and the like. One species, the acorn barnacle, has no stalk, but has a hard, acorn-shaped shell of many leaf-shaped valves.
       The structure of the barnacle can best be seen in the goose barnacle. It has a leathery stalk and six pairs of jointed feet. At the base of the shell is a cement-gland containing a secretion which enables the barnacle to adhere to any substance. These forms are widely distributed and are common in salt waters everywhere; they are not found in fresh water.
       Barnacles feed on small marine animals brought within their reach by the water and secured by their tentacles. Some of the larger species are edible. According to an old fable, these animals produced barnacle geese.

Gooeneck barnacles booming of B. C. coast.