The largest living organism on Earth is a honey fungus species known as Armillaria ostoyae. Located primarily in the Malheur National Forest in Oregon, this fungus covers an area of approximately 2,385 acres (965 hectares) underground. This organism is estimated to be around 2,500 years old, making it one of the oldest living organisms as well. The fungus primarily spreads through its underground mycelium, decomposing organic matter and interacting with various plant species. Its sheer size and extensive network of growth make it a fascinating example of life's persistence and adaptability in nature.