This 2007 photo shows Lake Magadi in Kenya, a carbonate-rich lake whose bed is made of volcanic rock. The lake's salty water is rich in microbes and it attracts other life, including these flamingoes and zebras.
Colored dots show the level of phosphorus measured in different carbonate-rich lakes around the world. Existing carbonate-rich lakes can contain up to 50,000 times the levels of phosphate found in seawater, with the highest levels measured in British Columbia's Goodenough and Last Chance lake system (yellow dots).