If you've never heard of guano this is a name used for the excrement of cave-dwelling bats, sea birds, seals, or birds in general. It was also used in the past to provide one of the ingredients needed for gunpowder production. Potassium nitrate (the chemical compound guano happens to be rich of) is used also for fertilizer and fireworks. And no, the guano itself is not explosive. Nitrogen, phosphorus, potassium and other compounds of animal waste can result in increased crop production through their fertilizing effects, in addition, the organic carbon improves soil fertility.
Animal waste material is mainly composed of indigestible fibers. To a large extent this refers to herbivorous animals. Because of their quality and quantity, elephant excrements are great source for paper production. The patties are collected, cleaned, spun, dyed, and dried to make paper. Funds raised by selling the end product are used mainly to support preservation project and zoos. Other endangered species used for such projects is the panda.