Poop comes in all shapes and sizes, but one kind of marsupial produces oddly symmetrical, six-sided feces that have had scientists scratching their heads. Patricia Yang, a mechanical engineering fellow at Georgia Tech, decided she needed to get to the bottom of why wombats expel poop cubes—the only known species to do this organically—and so she and her team set out to study the Australian marsupial's digestive system to try to solve the mystery, Phys.org reports. Yang presented their findings at the annual meeting of the American Physical Society's Division of Fluid Dynamics, explaining that the researchers examined the insides of two wombats that had been euthanized after being hit by cars in Tasmania.
"We opened those intestines up like it was Christmas," study co-author David Hu says, per Science News. The "gift" they found inside, per CNN, was the discovery that as the feces of the wombat—which can produce up to 100 poop cubes each night—moves into the last 8% of the animal's intestine, it shifts from a liquidy state to a solid, morphing into cubes about three-quarters of an inch in length. The scientists then inflated a balloon inside the intestine to find that the soft tissue of the wombat's intestinal walls were quite elastic, allowing the cubes to form. The reason that perhaps underlies the blocky excrement? Wombats, which don't see so well, stack their stinky poop to mark their turf and let other wombats know where they are. If the poop specimens are shaped like cubes, they won't roll away. (An Aussie pol used his vacation time to help wombats.)