The horse rectum and anus are a marvel of engineering. Together, they’re capable of expelling waste, segmenting waste, and cleaning themselves, with one contraction performed by a single muscle.

As the sphincter contracts, it pushes out the waste, while also tightening to divide the waste into precisely segmented portions. If you weigh the individual pieces of waste, they weigh the same, within only a half ounce or so of each other.

After the waste is expelled, before the sphincter relaxes, it squeezes the rectum in the direction of the anus, effectively cleaning the rectum of any remaining waste.

This design has been replicated mechanically and applied to countless manufacring processes. Just about any time some amount of fluid needs to be precisely portioned out on an assembly line, it uses a device that was designed to be basically a mechanical version of a horse’s asshole because it does such a good job of dispensing consistent quantities while minimizing waste, requiring very little maintenance and upkeep, and being very simple to build.