Why is wombat poop cube-shaped?

Direct link to the goods:

(warning: cubic poopy pic)

https://archive.today/2gM3z/106eb6129ecf07a4af55c0338fb9ce00...

> The wombat intestines have an irregular shape. Yang observed two distinct ravine-like grooves, where the intestine is stretchier, which she believes helps shape wombat digestive tract contents into cubic doo-doo [sic].