Why do wombats poop cubes?

The wombat’s digestive system is a geological factory that turns grass into perfect 90-degree bricks. A single wombat can produce up to 100 cubes of scat in a single night.

For a long time, people thought wombats had square-shaped sphincters, but the secret is actually in their intestines. The last section of the wombat's gut has varying levels of elasticity—two sides are stiff and two sides are flexible.

As the waste dries out, these uneven contractions mold the waste into a cube. This is an evolutionary advantage because wombats use their droppings to mark territory on rocks and logs. A round dropping would roll away, but a cube stays exactly where the wombat put it.

Wombats have the slowest metabolism in the mammal world, taking up to 14 days to process a meal. This long transit time allows the body to squeeze every drop of moisture out of the food, making the final cubes extremely dry and stable.

Human engineers are currently studying these intestines to find new ways of manufacturing square shapes using soft materials instead of rigid molds.