
Scientists explain how wombats drop cubed poop - craftyguy
https://phys.org/news/2018-11-scientists-wombats-cubed-poop.html
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yesenadam
That link is well worth reading about _why_ they do it. There's no paper yet,
but this, from the abstract[0], addresses _how_ :

"In the final 8 percent of the intestine, feces changed from a liquid-like
state into a solid state composed of separated cubes of length 2 cm. This
shape change was due to the azimuthally varying elastic properties of the
intestinal wall. By emptying the intestine and inflating it with a long
balloon, we found that the local strain varies from 20 percent at the cube's
corners to 75 percent at its edges. Thus, the intestine stretches
preferentially at the walls to facilitate cube formation. This study addresses
the long-standing mystery of cubic scat formation and provides insight into
new manufacturing techniques for non-axisymmetric structures using soft
tissues."

Incidentally, I grew up in the Australian bush, about halfway between Sydney
and Brisbane, but never saw a wombat. (But often cockatoos, kookaburras,
rainbow lorikeets, spiders, ticks, leeches, snakes, wallabies, possums, and
once a tiger cat (tiger quoll) got into the chook pen.) On a recent holiday to
a tiny village near Canberra, everyone had stories about wombats taking up
residence in or under their houses, and I saw quite a few dead on the side of
roads.

[0]
[http://meetings.aps.org/Meeting/DFD18/Session/E19.1](http://meetings.aps.org/Meeting/DFD18/Session/E19.1)

