If you look carefully at rocks in mid- to high tidal level, you'll notice they're often yellowish or pinkish. This is because they're covered with microscopic plants, many of which are diatoms, tiny, single-celled plants with hard silica shells. These plants are the main food for many grazing animals on rocky shores. Grazing snails and limpets Many species of these animals live on rocky shores. They eat microscopic plants, lichen or seaweed, depending on which part of the shore they inabit.
Limpets are snails which have a cup-shaped shell instead of a coiled one.
They use a large, flat foot to tightly clamp the rock. Barnacles Barnacles attach themselves to one spot on the rocky shore and never move, not even to feed. Using specialised legs, they catch food as it floats by in the waves. Barnacles' shells are made of several plates. Their size and shape depends on whether they're exposed to big waves.