There are only 65 known species of bioluminescent fungi, most of which are found in the tropics. That includes this Mycena luncentipes, recently found in Brazil. These natural night-lights have been admired for centuries. The Greek philosopher Aristotle and the Roman naturalist Pliny the Elder both refer to them in ancient texts, and in 1652 the Swedish historian Olaus Magnus described Scandinavians using the light from "pieces of rotten oak bark" to find their way in and out of the forest late at night. More recently, World War I soldiers attached the fungi to their helmets to help them see in the trenches.