Actually, what I find much more fascinating than koala farts is wombat poop. It's cubic, and Wikipedia has interesting things to report on it:
'They are not commonly seen, but leave ample evidence of their passage, treating fences as minor inconveniences to be gone through or under, and leaving distinctive cubic feces.[5] As wombats arrange these feces to mark territories and attract mates, it is believed that the cubic shape makes them more stackable and less likely to roll, which gives this shape a biological advantage. The method by which the wombat produces them is not well understood, but it is believed that the wombat intestine stretches preferentially at the walls. The adult wombat produces between 80 and 100, two-centimetre (0.8 in) pieces of feces in a single night, and four to eight pieces each bowel movement.'
Stackable poop - what exciting times we live in! Equally interesting is its chosen method of defence:
'Their primary defence is their toughened rear hide, with most of the posterior made of cartilage. This, combined with its lack of a meaningful tail, makes it difficult for any predator that follows the wombat into its tunnel to bite and injure its target. When attacked, wombats dive into a nearby tunnel, using their rumps to block a pursuing attacker.[17] A wombat may allow an intruder to force its head over the wombat's back, and then use its powerful legs to crush the skull of the predator against the roof of the tunnel, or drive it off with two-legged kicks, like those of a donkey.'
Crushing skulls, oh my. And then, of course, there is the infamous combat wombat: