Wombat poo is cube shaped so they can mark their territory with it but no one knows how they make their poo square #advancedwombattechnology pic.twitter.com/fIvMhyRoWS — Diana S. Fleischman (@sentientist) November 3, 2016

The Australian burrowing animals called wombats are the only creatures who have feces in the shape of cubes, and the unusual appearance of their poo has led scientists to ponder a number of theories.

Is the poo shaped like a square so wombats can more precisely mark their territory without it rolling away? Or are the blocky poo formations used to build habitats?

Another popular theory for square wombat poo has to do with the wombat's dry living environment.

"They have to really squeeze every drop of moisture out [of their food]," Mike Swinbourne, a wombat expert at the University of Adelaide in Australia, told National Geographic on Monday. Apparently, a dry climate makes the poo form more rigid geometric shapes with sharp corners.

Swinbourne also suggested that in zoos, where wombats have easy access to water, their poo is much less cubic in shape.

Patricia Yang, an engineering researcher at the Georgia Institute of Technology, thinks there's yet another reason behind the cube-shaped poo, and presented her new research Sunday at the 71st Annual Meeting of the APS Division of Fluid Dynamics.

Yang studied and compared the intestines of a deceased wombat with that of a pig to determine if the differences in the shapes of the intestines would affect the shape of the animals' droppings.

Yang and her team of researchers inflated skinny balloons inside the wombat and pigs intestines to measure the stretchiness.

They then discovered that compared with the pig's intestines, which had uniform elasticity, the wombat's intestines were a more irregular shape that included two distinct narrow gorge-like grooves. This made the wombat's intestines stretchier, which could explain the square poo shape.

Yang plans to continue her research to better understand how a cube poo shape can be manufactured with an intestine that has two sides instead of four.

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