The wombat that makes cubes

The wombat is the only animal in the world that poops in cubes. And it isn't a whim of nature: there is a very specific reason.

Its gut is extremely long and digests for almost two weeks. Along the final stretch, the intestinal walls have stiff zones and elastic zones alternating. Over tens of thousands of contractions, those differences slowly mould corners until they shape an almost perfect cube.

What for? The wombat marks its territory by leaving its droppings on rocks and logs. And a cube, unlike a little ball, doesn't roll or fall off. It stays exactly where its owner put it.

Evolution didn't design a cube out of elegance. It designed one because a cube doesn't get away.

Source: Science (AAAS), "How do wombats poop cubes? Scientists get to the bottom of the mystery".