Microscopic life thrives in Yellowstone's geothermal features. Many thermophiles take up residence in the extremely hot pools of water or colonize the sometimes slightly cooler runoff channels of these features. Thermophilic communities form and grow in geothermal features in a number of ways. Some species will form long, flexible structures called streamers in the fast-flowing water of runoff channels. Certain thermophilic species can also form mats or layers of archaeal and bacterial communities that are adapted to specific temperature and light conditions within the mat. Thermophlic bacteria and archaea are often brightly colored by photosynthetic pigments (chlorophylls or carotenoids) and show distinct zonations according to their specific temperature tolerances.