A team of scientists claims to have unraveled one of the animal kingdom's more peculiar mysteries: why wombat poop is cube-shaped.
The wombat, native to Australia, produces about 80 to 100 cubes of poop each night. It is known to use the dung to mark its territory, depositing piles of the stuff outside burrows and on top of rocks and logs, according to Australian Geographic.
But how the wombat produces the cubed shapes is a phenomenon that has puzzled many observers of the furry marsupial.
Researchers, led by the Georgia Institute of Technology's Patricia Yang, said they have uncovered the digestive processes behind the mystery and presented their findings at the 71st Annual Meeting of the American Physical Society's Division of Fluid Dynamics in Atlanta on Sunday.
The wombat's cubed faeces is a trait that's unique in the animal world, the researchers said, as cubes are usually created by cutting or molding.
"In the built world, cubic structures are created by extrusion or injection molding, but there are few examples of this feat in nature," authors of the project said in the study's abstract.
To solve the puzzle, the team examined the digestive tracts of wombats that had to be euthanized following vehicle collisions in Tasmania, Australia.
The wombat takes about two weeks to digest its food and researchers found that as faeces move into the final 8% of the intestine, it changes from a liquid-like state into solid matter. At that stage the dung takes on the shape of separated cubes measuring about two centimeters in length.
By inflating the intestine with a long balloon, the researchers found that the wombats' intestine walls stretch unevenly, allowing for the formation of the cube shapes.
"The local strain varies from 20% at the cube's corners to 75% at its edges," the team said. "Thus, the intestine stretches preferentially at the walls to facilitate cube formation."
The study's authors said the findings could have implications beyond the natural world, by helping to provide insight into new manufacturing techniques.