Amphibious worms that, for unknown reasons, seem to prefer living in contaminated waters and marsh-like areas. Researchers have discovered that these creatures actually have organs that allow them to digest and absorb mercury from the polluted waters.

Some scientists even claim that these creatures are like giant living filters and that any body of water that a Yondo-Worm has lived in for long periods of time eventually becomes drinkable again. Although many worm-type bio-engineered creatures are found in forests and deserts, this amphibian-type worm is only found in the Li Vis region.