No you didn't take anything to make you hallucinate. Some mushrooms and other fungi just glow, and this phenomenon is a mystery dating back to ancient times. Now, scientists have created some fake, glowing mushrooms and scattered them in a Brazilian forest in the hopes of once and for all solving this mystery.

The question of glowing mushrooms goes all the way back to Aristotle, according to Jay Dunlap, a geneticist and molecular biologist at the Geisel School of Medicine at Dartmouth College in Hanover, N.H. He says over the years people have thrown out various explanations for the light - everything from "it's a useless byproduct of metabolism" to "it attracts insects."

Dunlap and some of his colleagues published a series of experiments in the journal Current Biology that suggest at least one type of these glowing mushrooms actually controls when it glows. The glow lures bugs that then spread its spores throughout the dense forest, where there is at least a little wind.

The fungus in question is the Neonothopanus gardneri, a mushroom that grows at the base of young palm trees in coconut forests in Brazil and emits an eerie green light.

"You just have to turn off your flashlight and the mushrooms stand out if they're there," says Hans Waldenmaier, a researcher in the lab of Cassius Stevani, of Brazil's Instituto de Quimica-Universidade de Sao Paulo. "On a totally dark night, without any moon, if you have your light off," Waldenmaier says, "these green mushrooms are basically the only light source you see in the forest besides the fireflies."

Work in Dunlap's lab demonstrated that the eerie glow seemed to operate on a biological clock, suggesting that it's glow wasn't simply by accident. "We found that light was made mostly at night, and not mostly during the day," says Dunlap.

In an effort to understand why these mushrooms glow, researchers created fake fungi out of acrylic resin and placed an LED that emitted the right kind of green like much like the real mushrooms. Researchers then covered the devices with a type of sticky glue and placed them around the forest.

The impostors "roughly look about the same as the mushrooms we find out in the woods," says Waldenmaier. "We figured that this was a good way of replicating the mushrooms, but without the scent of the mushrooms, which could be attracting the insects."

So what did the researchers discover? Flies, ants and beetles were all found in greater numbers on the mushrooms that were lit compared to the ones that remained dark. For their next step, researchers plan to use infrared cameras to get a better idea of what the insects are actually doing there.

"We basically observed to see if there was any difference in the insects that were attracted to the ones that were lit up with the green light and the ones that were dark," says Waldenmaier.

Light production isn't actually common in fungi. Scientists have identified about 100,000 different fungal species, but out of those only 71 of them glow.