Many have 5 arms and look like stars. Others have 40 arms. They look like sunflowers. Sea stars have a bumpy body covered with small spines. Hundreds of tube feet help them to hold on to things and to move around.
Sea stars eat clams and mussels.
The sea star holds on to the clam or mussel shell with its tube feet. Stomach juices dissolve the meat of the shellfish which is then eaten by the sea star. Sea stars can grow new parts. If they lose an arm it will grow back. It takes a long time though.