To study silicon cycling, University of Antwerp biologist Jonas Schoelynck and his colleagues analyzed samples from the Mara River, which runs through the Maasai Mara National Reserve, a savannah in Kenya. The authors compared the chemical composition of the water with the local hippo population’s daily habits. They concluded that this poop introduces 0.4 metric tons, or roughly 800 pounds, of silicon into the Mara River every day. That’s about 76 percent of the river’s entire downstream silica flow. Other sources include soil erosion (the hippos themselves get their silicon by eating the roots and dusty leaves of plants) and the contributions of other, less legendary poopers.