Their range is from Alaska to Alta California. Thatched Barnacles can be found natively in California. Barnacles belong to a family called crustaceans that include lobsters, crabs, and water fleas. Barnacles can attach themselves to just about anything. Their favorite places are on rocks and pilings of piers.
Barnacles grow in six neatly fitted plates that overlap to form a ring.
A sliding door of four additional plates closes to protect the animal when the tide is out. With the door plates shut, it is fairly safe from its enemies. The door opens to let the barnacle feed when the tide comes in. Barnacles eat plankton. Acorn Barnacles, Tetacalita Squanosa , are shaped like tiny volcanoes.