The green glow emitted by wood-decaying mushrooms and other fungi is sometimes referred to as “foxfire”. This light is bright enough to see by, and was suggested by Benjamin Franklin as a light source for the early wooden submarine, the Turtle. It was also used by Tom in Sawyer to light his underground passages in Mark Twain’s seminal novels. Over 40 species exhibit the glow, including members of the genus Omphalotus (Jack O’ Lantern mushroom, ghost fungus), the honey mushroom, and many others. Nearly all use the luciferin illudin, and hence are toxic to ingest.