Dung beetle
Dung beetles eat the dung of herbivores and omnivores, and prefer it to any other kind of dung. They may also feed on mushrooms and rotting leaves and fruits. One species living in South America, Deltochilum valgum, is a carnivore which eats millipedes. Those that eat dung do not need to eat or drink anything else, because the dung provides all the necessary nutrients.