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Nº 007 · Nature · 45 sec

Why does the wombat make cube-shaped poop?

A round gut shapes cubes. Researchers only recently worked out how.

A female wombat with her young in front of the burrow
Photo: Charles J. Sharp · CC BY-SA 4.0 · Original
A cube-shaped piece of wombat poop on dry grass
Not a work of art but a wombat dropping: flat sides, distinct edges. An adult wombat leaves 80 to 100 of these pieces per night.Photo: Bjørn Christian Tørrissen · CC BY-SA 3.0 · Original

Soft and stiff in turns

Researchers dissected wombats and found that the cubes form only in the last sixth of the gut. There the gut wall has regions twice as thick and four times as stiff as others. When the gut contracts, the stiff sections move faster – and corners form.

What's the point?

Wombats mark their territory with their poop, often on raised spots. The usual guess: cubes don't roll away. Solving the puzzle earned the 2019 Ig Nobel Prize – an award for research that first makes people laugh, and then makes them think.

Fits with this

  • Nº 005 · Nature · 45 sec

    One animal. Three hearts.

    Two pump blood through the gills, one through the body – and that one takes a break when it swims.