Colorado is home to Sulphur Cave, which is exactly what it sounds like: A big, nasty hole that's filled with deadly gas and dripping with acid. Nothing should live there. It's basically hell on Earth. But then, scientists discovered clumps of limnodrilus sulphurensis wriggling around on the cave floor. In order to get in deep enough to find these remarkable creatures, the same gigantic fans that ventilate sewers were used to dispel much of the gaseous sulphur in the air. Once inside the cave, scientists were greeted with a small if icky ecosystem which also consisted of snottites — dangling, stalactite-like blobs of gooey single-celled bacteria. It's believe the worms huddle together and eat bits of bacteria that grow on or drip down to the cave floor.
David Steinmann, a research associate at the Denver Museum of Nature and Science, believes there could be some potential medical benefits from studying these worms besides their resistance to sulphur compounds that are deadly to humans. Specifically, their bright red colour comes from their blood's ability to bind extremely well to oxygen, which could be useful to understand for humans exploring similarly oxygen-poor environments.