If you're interested in animal poop, then you'll find the subject of wombat poo a fascinating one. Wombats produce cube-shaped scat which they use to mark the area around their burrows. The wombat will leave these droppings on fallen tree trunks or stones in order to make them more prominent. The droppings have flat sides to stop them from rolling away.
Wombats are a nocturnal marsupial native to Australia. They navigate primarily by smell, so droppings are an effective means of establishing territory to other wombats. A single wombat will produce up to 100 manure pellets every evening. The distinctive shape is the result of an extremely long digestive process which produces very dry and compact dung.
More about wombats:
I still wonder how the poop gets into a square/cube shape. Apparently all comes out well in the end. What do they mainly eat?