Glow-in-the-dark mushrooms have a newly discovered chemical to thank for their shine

You’re not tripping — these mushrooms really do glow. And now, we have a better idea how, thanks to a study published today in the journal Science Advances.

More than 100 years ago, a naturalist named George Gardner visited Brazil and saw children playing in the street with what he thought were giant fireflies. They turned out to not be insects, but big, glowing fungi that grow on rotting palm fronds. The species became known as Neonothopanus gardneri.

Recently, scientists discovered why the mushrooms glow. They planted faux-fungi lit by LEDs in the Brazilian Coconut Forest and saw that the nighttime luminescence attracts beetles, flies, wasps, and ants like, well, moths to a flame (sorry). These insects are key for spreading the mushroom’s spores so the mushroom can reproduce and colonize new food sources.

At least 80 other species of fungi emit light. The phenomenon, called bioluminescence, has been documented in mushrooms since Aristotle reportedly described glowing, rotting treebark — called foxfire or cold fire.

But how exactly fungi like N. gardneri and foxfire luminesce has been somewhat of a mystery. Often, when a creature like a firefly glows, it’s because of a class of molecules called luciferins. (The name is derived from “lucifer,” which is Latin for “light-bringer.”) They react with oxygen and another reaction-speeding chemical to create a high-energy product that emits light. This light-emitting product is called an oxyluciferin.

While scientists had recently figured out how luciferin is structured, they hadn’t yet discovered what the light-emitting products looked like. So the researchers collected samples of N. gardneri from the Brazilian Coconut Forest, pulverized them into a slurry rich in the fungus’s reaction-speeding enzyme.

Then, they used that slurry to produce the light-emitting oxyluciferin in the lab in large enough quantities that the scientists could sketch out the structure for it. Further experiments showed it was possible to create different versions of oxyluciferins that emitted different colors of light by tweaking the structure of the luciferin fuel.

Fluorescent molecules already play an outsized role in biological research: scientists use them to track cells and proteins. This new discovery could produce a new arsenal of luminescent molecules for research. Plus, they’re pretty to look at.