The world's largest living thing isn't an elephant, a whale, or a giant squid. In fact, the largest single organism on earth is actually a fungus. The most gigantic, and maybe the most ancient, organism on Earth resides in the Blue Mountains of the US state of Oregon. It lives underground, and has killed scores of living things in its possible thousands of years of existence. No, it's not a gigantic ogre—it's a mushroom-producing fungus the size of 1,600 football fields, and it wipes out trees by the hundreds.

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