This article originally appeared on VICE US.
Wombats take the concept of “shitting bricks” quite literally, and are known to drop around 100 curiously cubic poops every night.
On Sunday, the secret behind this square scat was revealed at the annual meeting of the American Physical Society’s Division of Fluid Dynamics in Atlanta, Georgia. There, Patricia Yang, a postdoctoral fellow at Georgia Institute of Technology, presented research demonstrating that cube poop is produced by uneven elasticities within the wombat digestive tract.
This process is “unique in the animal kingdom,” according to the presentation abstract.
To probe the intricacies of wombat poop, Yang and her colleagues examined the digestive tracts of two wombats that were euthanized after road collisions in Australia. She got the dead wombats from Scott Carver, a wildlife ecologist at the University of Tasmania, who froze the specimens before sending them to the US for further study.
David Hu, a mechanical engineer at Georgia Tech and co-author of the study, said “we opened those intestines up like it was Christmas,” according to Science News.
The wombats’ intestines were indeed packed to the brim like stuffed stockings. Due to their unusually slow metabolic rates, wombats take about two weeks to digest their food, which can lead to large buildups of poop that can cause their intestines to bulge.
Yang’s team mimicked the process by inserting balloons into the wombats’ intestines and blowing them up to observe the contours and flexibility of their digestive system. The inflated balloons revealed that the tail end of the wombat digestive tract is disproportionately stretchy in some places and stiff in others.
This is where the magic happens, according to Yang and her colleagues. Wombats solidify and sculpt the turds using the lopsided elasticity of the intestinal walls in the final tenth of the tract.
Wombats often arrange these cubes into mounds that mark their warren territories, essentially laying bricks straight from their bums. This territorial impulse could explain why these animals evolved to produce feces that can be easily modeled into stable kairns of poo.
Yang and her colleagues plan to continue their research into this scatological superpower, and suggest that humans might even be able to learn some manufacturing tips from the extraordinary production facilities inside wombat butts.