What is the size of the biggest ever recorded?

The biggest ever recorded organism is a honey fungus (Armillaria ostoyae) located in the Malheur National Forest in Oregon, USA. This fungal network spans approximately 2,385 acres (965 hectares) and is estimated to be thousands of years old. While individual mushrooms are relatively small, the underground mycelium can cover vast areas, making it the largest living organism by area.