Cryptobiotic soil. Cyanobacteria and other organisms forming a living crust" (brown/white) on the surface of soil. Cryptobiotic soil is formed from cyanobacteria (blue-green algae), lichens, mosses, algae, fungi and bacteria. These organisms bind the soil particles together, reducing erosion by wind and water. They also convert atmospheric nitrogen into a form which can be used by plants growing in the soil, and increase surface roughness, providing protected places for seed germination. Cryptobiotic soils are found throughout the world, but are most common in arid or dry environments. Photographed in the USA."