Swiss scientists have found what they say may be Europe's biggest mushroom - covering an area about the size of 35 football pitches.
The fungus is a formidable parasite, which can kill trees
The fungus was discovered in a national park near the eastern town of Ofenpass, said the Federal Institute for Forest, Snow and Countryside Research (WSL).
Spanning 35 hectares (86 acres), the mostly underground fungus is believed to be 1,000 years old, the WSL added.
The Honey Mushroom (Armillaria ostoyae) is edible, but it can kill trees.
"The majority of the fungus is an underground network that looks a bit like shoelaces," WSL's spokeswoman Muriel Bendel said.
"The surface mushrooms look like the normal type you would pick, and are brown to yellow," the spokeswoman added.
Although harmless to humans, certain species of the vast underground organism can colonise trees, gradually strangling them, scientists say.
The fungus is only visible in autumn, when its mushrooms break through the earth and grow around the roots of trees, the WSL said.
The Swiss fungus is considerably smaller than another Honey Mushroom growing in the US.
Found in the Malheur national forest in Oregon, that fungus covers 890 hectares (2,200 acres) - making it the largest living organism ever discovered.