Goose barnacles form dense clusters in the California mussel beds. They attach to the rocky substrate with a flexible stalk that is cemented to the rock. The body is covered by a number of calcareous plates that protect the body from wave action and desiccation when the water recedes. The goose barnacle feeds on larger food materials than the acorn barnacle. It usually feeds upon amphipods and other creatures up to the size of houseflies. Many delicate creatures are found among the bases of the California mussels and goose barnacles.