It's a biological curiosity that baffles scientists and has fascinated the Internet.
Now, researchers believe they've solved one of wildlife's most puzzling puzzles: how to produce Wombat's cuboid piles.
The six-sided dung parts of the chubby marsupials are unique in nature. And they produce them abundantly and deposit between 80 and 100 cubes every night.
Wombat's characteristic defecation has an important function: the animals can pile up their stools to mark their territory and communicate through scent.
Due to the flat sides of the pellets, they can be placed prominently on tree trunks and stones without rolling them off.
Scientists, however, have always been unsure how wombats – which have circular anus – make their excrement into their unusual shape. Now, a team of US mechanical engineers and Australian biologists believe they've eliminated all doubts.
Patricia Yang, a postdoctoral fellow at the Georgia Institute of Technology, examined differences in wombats Soft tissue structures could explain their strangely shaped crap.
"The first thing that drove me is that I have never seen anything so funny in biology. That was a mystery, "said Ms. Yang, who studies fluid hydrodynamics, including blood, processed food, and urine in carcasses.
She added, "I did not even believe it was right in the beginning. I googled and saw a lot about cube-shaped wombats, but I was skeptical. "
The researchers examined the digestive tract of Wombats that had been hit by road vehicles in Tasmania (Australia).
At the end of the intestine, they found that the feces were changing from liquid to solid states consisting of small, discrete cubes. The researchers concluded that the different elastic properties of the intestinal walls of wombats allowed the formation of cubes.
In the artificial world, cubic structures are usually made by injection molding or extrusion. In nature, however, the shape is extremely rare: Wombats are the only known species that can produce cube organically.
Ms. Yang said her findings could affect manufacturing and contribute to the scientific understanding of soft tissue transportation.
"We currently have only two methods of making cubes: we shape or cut them. Now we have this third method, "said Ms. Yang. "It would be a cool method for the manufacturing process – how to make a soft tissue cube instead of just forming it.
"We can understand how to move these things in a very efficient way."
Scott Carver, an Australian biologist involved in the study, added: "Both in Australia and internationally, there is a general interest in how and why wombats produce cube-shaped excretions.
"Many ideas, some more entertaining than others, have been suggested to explain this, but no one had investigated the cause until this study. This is a fantastic collaboration that demonstrates the value of interdisciplinary research for new scientific discoveries. "
This week, researchers will present their findings at an annual meeting of the Division of Fluid Dynamics of the American Physical Society in Atlanta, Georgia.