Grooved goose-neck barnacle
Another type of barnacle that is commonly found attached to floating debris washed up on beaches, driftwood, and ship hulls is the Goose-neck barnacle. It has a long, fleshy stalk ending in a flat body formed of several connected calcareous plates.
Barnacles feed through feather-like appendages called cirri. As the cirri rapidly extend and retract through the opening at the top of the barnacle, they comb the water for microscopic organism. When the tide goes out. The barnacle closes up shop to conserve moisture. As the tide comes in, a muscle opens the door so the feathery cirri can sift for food.