Seaweeds are important economically since they yield agar, alginates and mucilages. They are invaluable as stockfood and manure. Some seaweeds have medicinal properties. Lastly certain seaweeds are edible and nutritious. The most abundant Indian seaweeds are those that yield agar and algin. The former comprise red alga: of the genera Gelidium, Sarconema, Gracilaria and Corallopsis.