The literature on desert cyanobacteria appear to indicate that they mostly colonise the soil crust or cracks in rock, where they play an important ecological role in the breakdown of rock into soil. More specifically for example, cyanobacteria have been found salt rocks in the Yungay region. Cyanobacteria photosynthesise; therefore, they require access to sunlight. Fungi and lichens tend to grow in the shade, while cactus roots are underground.