Deep inside Glenrock State Conservation Area, groups of fungi hunters have been gathering each night to take in a strange natural phenomenon: ghost mushrooms.
The bioluminescent fungus blooms from decaying timber, emitting an otherworldly green light.
"There are more than 100 species of mushrooms that glow," Associate Professor Karen Livesey said.
"It's not as rare as you might think, and we have other examples of plants and animals that bioluminesce, too."
Associate Professor Livesey runs Glenrock Ghost Fungus Tours, and has spent the past few nights taking 13 groups, drawn in by the unusual glow.
Nine of the tours sold out, which was a happy surprise, she said, given tickets were mostly made available the day of each tour. Dr Livesey, a physicist, said it had been a reward to bring a diverse set of mushroom hunters into her world.
"I had a five-year-old boy who had heard about ghost mushrooms on the Gardening Australia podcast for kids," she said. "He had demanded to come on the tour and had never stayed up that late before.
"Can you imagine?"
Dr Livesey, a former head of physics at the University of Newcastle, said her interest in the mushrooms might seem like a divergence from theoretical physics. But she said she had broad interests, and there were connections.
"I was surprised to find that you actually need to know some quantum science to understand where the light is coming from," she said.
A career spent teaching undergraduates to navigate the science of the universe, and to find the same joy that had captivated her in the field, went a long way in understanding the alien qualities of a glowing fungus.
"They naturally produce two chemicals that react to produce a third compound in an electrically excited state. It eventually falls down into a relaxed state, and when it does that, it releases energy," she said.
"A specific amount of energy corresponds to a specific colour of light, and in this case, it is green light."
It was thought that the mushrooms glowed for an evolutionary advantage. Perhaps, glowing attracted insects that would eat the mushroom and help the species to propagate. However, recent research disproved the insect theory, leaving scientists to look more closely at how the fungi interact with the forest. Almost all of the plants that grow in the reserve and elsewhere rely on subterranean fungi to survive, she said.
"There is a symbiotic relationship between a lot of fungi and the plant roots, where the fungi gets a bit of energy from the root and in return produces nutrients for the plants," she said.
"So, when we see them, it is a good sign that the ecosystem is healthy.
"But we don't actually know if there is an evolutionary advantage to the ghost fungus glowing. We just don't understand ... yet."
The ghost fungus only appears in the Newcastle region for a short period each year, normally in April or May after some rain. There are no more tours expected this year.
