Scientists have finally found an explanation to the mounds across South America which has been baffling them for decades.

Researchers have previously assumed the conspicuous landscape feature that covers 26,000 square miles was formed by erosion caused by flooding. But recent study published in the journal Public Library of Sciences One, claims that these mounds are earthworm poops, scientifically known as surales. The discovery marks the first time they have described the formation.

By using remote sensing techniques, satellite images and aerial photographs and taking a sample of the mound for physical and chemical examination, the researchers learned that earthworms cast account for around one half of the total soil mass of surales.

"Surales are formed when large earthworms feed in shallowly flooded soils, depositing casts that form 'towers' above water level. Each earthworm returns repeatedly to the same spot to deposit casts and to respire. Over time, the tower becomes a mound," the researchers explained.

Earthworm surales are unique to South America, the researchers claim. One of the earthworms identified is from the South American genus Adiorrhinus . The previously unknown worms, which can grow up to 5ft. long were the main builders of the mound. Live Science noted that a single species of giant andiorrhinus worm made up almost 93 percent of worm biomass. These worms that form the surales have the ability to change the landscape, far wider than people have thought. The researchers added that the shrubs that grow nearby also helps in the process of building these mounds that can grow up to 16 feet wide and 6 feet high.

"We found that surales are much more frequent and widespread than was first suspected. We detected them in different zones within an area of about 75,000 square kilometres (29,000 square miles), an area greater than that of the Republic of Ireland," Professor Doyle McKey, an ecologist at the Centre for Functional and Evolutionary Ecology in Montpellier who was one of the authors of the research told Daily Mail UK.

Study co-author and archaeologist José Iriarte of the U.K.'s University of Exeter said the discovery can change how we think about human verses naturally-built landscapes in the region.