The overgrown jungles of our world are some of the most remote and unexplored places on the planet, but this does not mean that they have always been untouched by humans. From inexplicable abandoned planes to terrifying wolverine frogs and giant cave systems that hold an entire world on the inside, grab your popcorn and get comfy as we count down the 15 most mysterious jungle discoveries in the world that have changed the way we look at the forests dotting our planet.