Hijiki is a porous, black seaweed with a surface that is less viscous but has more texture than other seaweeds. It is normally sold dried and should be reconstituted with water before use. Hijiki contains a lot of calcium and fibre. It also contains a high level of iron. Hijiki is normally simmered with chopped vegetables such as carrots, fried tofu and beans, and seasoned with soy sauce and mirin, and served as a tasty side dish.