Poop Cube?

Wombats would be right at home in the world of Minecraft, where everything is made of square blocks. These fuzzy animals from Australia are the only organisms on Earth that make poop in the shape of cubes. So a few years ago, David Hu, a mechanical engineering and biology professor at the Georgia Institute of Technology, decided to find out why.

Wombats are marsupials—or animals that raise their young in pouches. They eat grass and leaves. After they eat, their meal passes through about 9 meters (30 feet) of intestines. This long, tube-like organ breaks down food and absorbs its nutrients. The process produces poop as waste. Two stiff bands of muscle run along the length of a wombat’s intestines. The bands squeeze the poop as it passes by. This creates feces with flat sides and edges.

“The reason humans can’t make square poop is that we don’t have those stiff parts on our intestines,” says Hu. Wombat poop is also drier than human poop—containing about 60 percent water, compared with our 80 percent. That helps it hold its cube shape.

Wombats poop on rocks and stumps to mark their territory. “The smell helps wombats and other animals figure out who lives there,” says Hu. He thinks the dung’s cube shape may help the poop stay put. “The squareness prevents it from rolling away,” he says. For puzzling out the purpose of wombat’s cubed poop, Hu won an Ig Nobel Prize—a humorous science award for research that makes people laugh and think.