Rockweed is a species of green algae that grows in intertidal areas on rocks. Its colour ranges from dark green, brown or even dark yellow. It is a short seaweed with forked tips. During the spawning season, the tips are swollen and bumpy, full of eggs and sperm.

Rockweed is slimy to the touch, an adaptation to prevent drying out when the algae is exposed at low tide. Many organisms hide under Rockweed to evade predators and also to avoid desiccation during low tide. Look amongst Rockweed and you will find hundreds of snails, limpets, amphipods, sea urchins and sea stars.