Ice algae and snow algae are algae and cyanobacteria which grow on long-lasting snow and ice fields like glaciers. When liquid water is available between the snow and ice crystals, they may color the surface green, yellow or red during the summer months. The red pigment of some species is an intracellular protection against excessive visual light and ultraviolet radiation of the sun, which otherwise can cause photoinhibition of photosynthesis or mutations. Without it, the algae at the surface would suffer chromosome breaks and DNA mutations.