The largest living organism in the world is an underground fungus in Oregon.
Why it is true
Known as Armillaria ostoyae, this fungus covers about 9.6 square kilometres in the Malheur National Forest, Oregon. Most of the organism is underground, in the form of a network of filaments called hyphae. It is estimated to be between 2,500 and 8,650 years old.
Source: USDA Forest Service
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