The Humongous Fungus: Crystal Falls' giant underground neighbor

In the hardwood forest near Crystal Falls lives a neighbor most towns would envy. It’s one single living thing, so old and so vast that it made headlines around the world. It’s a fungus — a honey mushroom called Armillaria — and almost all of it lives underground. Picture a web of root-like threads spreading silently through the soil. In autumn you might spot clusters of ordinary little mushrooms on the surface. Those are just the tips. The real creature is the giant network beneath, and all of it is genetically one individual.

The first published measurements came in a 1992 Nature paper. Researchers mapped at least 15 hectares, about 37 acres, and estimated a mass greater than 10,000 kilograms — roughly 11 U.S. tons. They put its age above 1,500 years and described fungi as belonging among the oldest and largest organisms on Earth. The nickname “humongous fungus” stuck, even after a larger Armillaria individual was identified in Oregon.

Later research made the local numbers much larger. A 2018 study sampled more widely and used whole-genome sequencing. It estimated that the same individual covered about 75 hectares, roughly 185 acres, weighed about 400,000 kilograms, and was at least 2,500 years old. Armillaria can live on dead wood and also infect trees, so “gentle giant” is better festival language than forest science.

Crystal Falls celebrates the discovery with the Humongous Fungus Festival. The program and dates change from year to year, so check the current listing before driving up. The fungus itself is not a marked attraction; most of it remains underground across a broad forest area.