The Leaf Barnacle is identifiable from other members of its species because the capitulum (top of the stalk) is covered with at least five cream-colored plates and surrounded by several whorls of overlapping scales. This makes the top of the animal appear similar to a stalk of asparagus. The usual stalk length is 4 inches (10 cm) high to 1-1/8 inches (3cm) diameter at the crown. Some have measured 6 inches (15 cm) in length. Barnacles living in the middle of the group grow to the greatest height and can live as long as twenty years.
Leaf barnacles eat by casting their cirri (feather-like tentacles) into the backwash of the waves and capturing large particles of detritus and crustaceans. Unlike other barnacles, they do not beat their cirri in a rhythm, but extend them into the water flow to catch their prey. These barnacles are often exported to the seafood markets of Europe where they are considered a delicacy.
Leaf Barnacles are common down to 100 feet (30m) below the surface. Often they live with California Mussels. Leaf Barnacles attach themselves in clusters to rocks at intertidal to shallow sub-tidal levels. The stalks are strong enough to withstand harsh surf waves that toss them around. They anchor themselves to various surfaces (which in some cases can include the bodies of Humpback Whales) by secreting a glue-like substance. They can be found from southern Alaska to Baja California.