Undercover robot boats disguised to look like crocodiles are taking over Kenya's Mara River. Their job? Measure the amount of hippopotamus droppings in the river and keep an eye on the water's overall quality. With more than 4000 hippos using the stream as a toilet, researchers suspect they're responsible for the fish that are dying off in the area. As dung settles in the water, bacteria form and suck up the oxygen that fish need to breathe. Data collected by the robots are still being analyzed, but the disguises were necessary to avoid attack by the extremely territorial hippo (which tolerates crocs).