Trigger It could be argued that mushrooms are among nature's strangest creations. If not the oddest, mushrooms are certainly among the most diverse, with roughly 14,000 known species around the world ranging from wildly colorful to dreadfully bland. They can kill you, or they can be absolutely delicious. In fact, the largest, oldest organism on the planet is a mushroom: the immense honey mushroom in Oregon's Malheur National Forest, which spans an incomprehensible 3,726,563 square meters, dwarfing a blue whale, let alone a paltry elephant. Meanwhile the cup fungus, according to the pleasantly named Mushroom Expert website, has a cap that spans just 4 millimeters.