At last! Scientists have cracked the mystery behind how wombats produce cube-shaped poop.

While it's common for animals like wombats to use their feces as a way of marking territory, what sets them apart is the unique shape of their droppings. Wombats are the only animals known to poop cubes, as reported by Science News. Researchers believe they've now uncovered the secret behind this unusual phenomenon.

Mechanical engineers David Hu and Patricia Yang from the Georgia Institute of Technology received a unique gift—two frozen wombats, unfortunately roadkill, from a colleague in Australia. Upon dissecting the animals, they studied their intestines and found them to be remarkably elastic. Wombats' intestines can stretch to two or three times their normal width when passing waste, a finding shared by the researchers at an American Physical Society meeting in Atlanta.

To examine how different sections of the intestine stretch, the researchers used thin balloons (the type typically used to make animal shapes) and inflated them within the organ. However, not all parts of the intestine were equally stretchy. Yang speculated that the more rigid areas might play a role in forming the edges of the poo cubes as waste moves through the final stretch of the intestine. (Wombat intestines range from 30 to 40 feet, based on another study on wombat digestion.)

The last eight percent of the intestine is where the feces transforms from a liquid-like consistency into solid, cube-shaped pieces, each about three-quarters of an inch long, according to researchers.

Wombats' cube-shaped droppings, as reported by Science News, have an advantage—they stack easily and don’t roll off rocks. Wombats typically produce between 80 and 100 droppings a night, and they like to leave them on rocks, logs, and dirt piles where they are clearly visible. The scent also aids them in navigating at night.

While wombats may be impressive in their digestive abilities, they aren’t the only animals whose feces seem to defy the laws of physics. For example, sloths can have a bowel movement that weighs up to a third of their body weight.