Lake Natron in Tanzania is one of Earth’s most extreme environments. Its waters are so alkaline—thanks to sodium carbonate from nearby volcanic rock—that animals that fall in can become eerily preserved, as if turned to stone.

These calcified remains are caused by the same mineral once used in Egyptian mummification. But despite its harshness, Lake Natron is a vital breeding ground for lesser flamingos, who thrive on its salty islands. The lake’s caustic waters help protect their nests, making it both deadly and life-giving.