They don't call wombats diff crackers for nothin', mate.
I live in Australia, and in wombat country. I am not kidding when I say that if your car hits a wombat (approximately the size of a largeish fox terrier) your car will never drive again. If a bus hits the wombat, the bus will never drive again either. I've seen a metre deep divot dug into the front of a jeep. It looked for all the world like it had been wrapped around a tree, then removed from the tree.
"What happened?"
"Hit a wombat."
"Struth! Where's the wombat?"
"It walked away, don't know where it went."
Their droppings are indeed cubes. I have seen them. The droppings are also black, and dense, like little cubical stones.
And if you put a fence post in a place they don't want the fence post, they will smash the fence post to matchsticks. By fence post, I mean a lump of hardwood six foot long, half a foot square, dug two or three foot into the ground. This they will splinter to matchsticks in a single night, I've seen it happen.
Never. Ever. Pick a fight.
With a wombat. They are DENSE, and we joke that they are made of the dark matter of the universe. They are definitely made of unobtanium, and someone once called the beast "natural tank" and I don't disagree.
Thank god they only eat plants.