Why Wombats Have Square Poop

For this one, let's go deep into science and examine one of modern biology's and zoology's biggest mysteries. Specifically, why can only the lowly wombat create poop in the form of cubes when no other species on earth can?

Wombats poop strategically to send messages to other wombats, which is weirdly practical. What messages are they? Most likely a territorial dispute to let other wombats know where they are. Additionally, it may be contained in a cube to stop it from rolling away. And while that's a fantastic explanation for why the wombat has poop cubes, it doesn't address the question of how. It's not like you could just will a poop cube to mark your territory if you wanted to do that. What then transpires in a wombat's butt?

Wombat dissection is involved in this horrible scene. Scientists investigated the intestines of a wombat that had perished in an accident and found that the animal had two grooves that were more elastic than the rest of the gut. The intestines are depicted in a 2D rendering as having layers of varying thickness and rigidity. The intestines make those peculiar-looking cubes and expel them out the back door once digestion is complete as muscles flex over the course of several days to extract all possible moisture and nutrients from the food being digested.