Scientists have only recently described this phenomenon. People who eat the mushroom Lanmaoa asiatica report the same hallucinations: they see little humanoid figures marching under doors, walking along walls, and hanging from furniture.

This tubular mushroom does indeed resemble a porcini, though it is slightly brighter in color, with a pinkish stem and a yellowish cap, BBC reports. It grows in Asian countries and is known for its rich umami flavor.

In China’s Yunnan province, during mushroom season from June to August, it is freely sold at markets and appears on restaurant menus. Meanwhile, doctors at one hospital prepare for an influx of patients with an unusual complaint: they see small creatures resembling elves. There are several hundred such patients every year.

The reason is that if Lanmaoa asiatica is prepared incorrectly, hallucinations begin.

“At one restaurant with mushroom hot pot, the waiter set a timer for 15 minutes and warned us, ‘Don’t eat until the timer goes off, otherwise you might see little people,’” says Colin Domnauer, a graduate biology student at the University of Utah and the Utah Museum of Natural History who studies these mushrooms. “It seems to be common knowledge in the local culture.”

Outside Yunnan province and a few other places, the mushroom is not treated as something ordinary and is seen as a mystery.

“There were many reports about the existence of this psychedelic [mushroom], and many people tried to find it but were unable to identify the species,” says Giuliana Furci, a mycologist and founder and executive director of the Fungi Foundation, a nonprofit organization dedicated to discovering, documenting, and conserving fungal species.

Domnauer hopes to determine what unknown compound causes such similar hallucinations and to understand what this mushroom can teach us about the human brain.

He first heard about the mushroom as a student from his mycology professor.

“It sounded so strange — that somewhere there is a mushroom that causes fairy-like visions reported by people from different cultures and eras,” Domnauer says. “I was puzzled and became curious to learn more.”

He and his team are still trying to identify the chemical compound responsible for the hallucinations. Based on tests conducted so far, it is likely unrelated to any known psychedelic substances. The “trips” caused by this mushroom are unusually long — from 12 to 24 hours. In some cases, patients remain in the hospital for up to a week. Because of the extreme duration and the risk of prolonged side effects such as delirium and dizziness, Domnauer has not yet dared to try the raw mushrooms himself.

According to Domnauer, these intense “mega-trips” may explain why in China, the Philippines, and Papua New Guinea there is no tradition of deliberately consuming L. asiatica for its psychoactive effects.

“It was always eaten simply as food,” he says. The hallucinations were an unexpected side effect.

There is another intriguing aspect: most known psychedelics tend to produce unique experiences that can vary not only between different people but even in the same person from one use to another.

L. asiatica, however, consistently causes visions of little people.

“I don’t know of anything else that produces such consistent hallucinations,” the researcher says.

Understanding the nature of this mushroom will not be easy, Domnauer notes. However, like research into other psychedelic compounds, scientific work on it could ultimately touch on fundamental questions of consciousness and the relationship between mind and reality.

Moreover, it may help explain the cause of spontaneous Lilliputian hallucinations in people who have not consumed L. asiatica. This is a rare condition: by 2021, only 226 such cases had been documented since the first description in 1909 that were unrelated to mushrooms. Yet for this relatively small group of people, the consequences can be serious — one third of patients never fully recovered.

According to Domnauer, studying L. asiatica could help scientists better understand the brain mechanisms behind these visions and possibly even develop new treatments for patients with similar neurological conditions.

“Now we may be able to understand which areas of the brain generate [Lilliputian hallucinations],” says Dennis McKenna, an ethnopharmacologist and director of the McKenna Academy of Natural Philosophy, a nonprofit educational center in California. He agrees that understanding the compounds in this mushroom could lead to the discovery of new medicines. “Whether there is therapeutic potential here — time will tell,” he adds.

Researchers estimate that less than 5% of all fungal species on Earth have been described so far. Therefore, Furci believes these studies hold enormous potential for new discoveries at a time when ecosystems are rapidly shrinking.

“Mushrooms contain an extraordinarily vast biochemical and pharmacological library that we are only beginning to explore,” Furci says. “An entire world of discoveries awaits us.”