The name derives from the long, flexible, extendable muscular stalk, like a goose's neck, that attaches to the substrate. Five bivalve-like calcareous plates protect the soft body. Goose barnacles live in groups attached to a variety of both floating and stationary objects, from pieces of driftwood and great whales to solid rocks, molluscs and other barnacles. As in acorn barnacles, the large, feathery limbs, or cirri, extend through the opened shell to filter small, floating edible particles from the water.