Earthworms are the engineers behind the 75000 km2,densely packed, regularly spaced, or mound-patterned landscapes,called surales, in the South American seasonal tropical wetlands, or according to a study published May 11,2016 in the open-access journal PLOS ONE by Anne Zangerlé from Technische Universität Braunschweig, Germany, or Delphine Renard from McGill University,Canada, and colleagues.
Source: phys.org