Bladder Wrack is a brown seaweed with small air bubbles that help it float and catch sunlight. Sea Lettuce is a bright green seaweed that looks like lettuce leaves. Both grow on rocks in rockpools and are very important because they provide food and shelter for many tiny animals like crabs, snails, shrimp, and small fish. These seaweeds also help keep the water clean and full of oxygen. The animals living in the seaweed use it for protection from predators and strong waves, making a busy, healthy community in the rockpool.