Cobbled and boulder shores are exposed to wave action and tides, and are periodically restructured by high-energy storm events. Drift seaweed and local algae support communities of organisms adapted to regular disturbance and grinding of rocks and cobbles, as well as the high temperatures and desiccation common to all shorelines. For example, many live largely below the surface layers. Stability of the substrate, and hence the biota, depends on the size of the cobbles and boulders. Some encrusting species or algae like cordgrass can stabilise these shores and allow a wider range of plants and animals to establish.