Antarctica’s Blood Falls looks exactly like what the feature’s name suggests. And those tiny beings offer clues as to how the mysterious formation came to be. The species are not believed to live in the underground, iron-rich saltwater lake that feeds Blood Falls (and that provides the feature’s signature color, thanks to the oxidation of the iron when it hits the air). Researchers collecting samples at Blood Falls. There is at least one more mystery to solve, too: Allen notes that phytoplankton like those found in the expedition usually thrive in areas that are relatively poor in iron—the exact opposite of Blood Falls.