The type of rock (eg. basalt or sandstone, boulder field or flat ledge) influences the way in which the rocky shore is eroded. Some rocks like basalt break up easier than others such as sandstones and this in turn gives rise to a wide range of habitats such as cracks or crevices within the rocks providing shelter and basins for rock pools.
The type of material a reef is made from also has a great influence on the animals and plants which live on it. Subtidal sandstone reefs, for example, are often undercut and have many ledges and crevices worn into them. The surfaces of sandstone reefs often teem with sponges, feather stars, urchins and anemones, while basalt reefs are more likely to support mobile animals such as Pacific Octopus, abalone and chitons. The number of caves and crevices in a reef will also contribute to the number of fish which seek shelter there.
Intertidal reefs also show differences in the marine life they support. Basalt rock platforms are warmer than sandstone and the plants and animals that live on basalt must be able to cope with higher temperatures. Basalt is also more likely to form boulders. These boulders provide microhabitat for many intertidal animals.