Postelsia palmaeformis, also known as the sea palm (not to be confused with the southern sea palm) or palm seaweed, is a species of kelp and classified within brown algae. The sea palm is found along the western coast of North America, on rocky shores with constant waves. It is one of the few algae that can survive and remain erect out of the water; in fact, it spends most of its life cycle exposed to the air.