Kelps can get very large. Some are over 300 feet long. When they wash inshore after a storm, their size is still impressive. Kelps are harvested as cattle food or to extract minerals and the components of their cell walls, a gummy material called algin. Algin is used commercially as a stabilizer in food products or shaving cream or cold cream.
Red algae are less common along the coast of California but they are present.
This often gives them a pink, rather than red appearance. Others are bright red in color. The genus Porphyra is cultivated as a crop in the marine waters of Asia. Other red algae is harvested for materials that can be extracted from their cell walls. These materials are caragheenan and agar.