Balanus perforates

Barnacles may look like molluscs, but they are actually crustaceans, like crabs and shrimps. They usually attach themselves to rocks in the intertidal zone (the zone that is alternately covered and uncovered by seawater as the tides come in and out), but can also be found on the hulls of boats and on the skin of some whales! When they are submerged in water, they stick out tiny feathery legs to catch the small planktonic particles they feed on. When not covered by water, they retreat into their shells.