Armillaria ostoyae is called honey fungus. It is the oldest living thing on Earth. It is about 2400 years old and spread over about 2000 acres of land. Armillaria ostoyae is the world’s largest species of land occupied. It grows in the forests of Oregon, USA. Its occupied area is more than 1665 football fields. It destroys many trees during its spread. Armillaria mellea species emit light in the dark. Some species contain toxins called amatoxins. Some species are poisonous and can cause immediate death to humans or animals.