For years, scientists in South America have been scratching their heads over mysterious bulges that form on the ground.
Some of them are actually quite large–measuring up to five metres in diameter and two metres in height. They’ve been found in the soil at the tropical grasslands of Orinoco Llanos (located in Colombia and Venezuela), and nobody has ever seen what makes them. One day you can walk by and see nothing, and the next, a mound that steadily swells larger as the days go by. They look like this:
Sometimes, they’re even large enough to protrude out of the water:
Experts so far have thrown around all kinds of theories to explain the phenomenon, many of which involve erosion, termites or other insects. But it turns out bugs have nothing to do with it, according to a new study published in the journal Plos One. The real explanation is, well, just plain nasty.
The mounds are caused by–wait for it–worm poop. Freaking worm poop. Which means these “mounds” are actually human-sized towers of crap.
“Mounds are initiated when large earthworms feed in shallowly flooded soils, depositing casts that form ‘towers’ above water level,” the study reads. “Using permanent galleries, each earthworm returns repeatedly to the same spot to deposit casts and to respire. Over time, the tower becomes a mound.”
In other words, worms crap in the same spot so many times, that the poop eventually makes the ground swell. Researchers found about half of the mounds are comprised of poop. Plus they’re so large and prevalent, that they actually have the ability to alter the natural landscape.
To make these findings, researchers analyzed aerial and satellite photography along with soil samples from the region. While satellite imagery might seem excessive for this kind of work, here’s what the mounds look like from above:
“This exciting discovery allows us to map and understand how these massive landscapes were formed,” Professor José Iriarte, from the University of Exeter’s Archaeology Department, said in a statement. “The fact we know they were created by earthworms across the seasonally flooded savannahs of South America will certainly change how we think about human verses naturally-built landscapes in the region.”
It’s now official, folks: ignorance is bliss.