It's like something out of a sci-fi movie — an ancient species of bug, glowing on the roof of an abandoned railway tunnel, deep in a remote forest.
And locals could not be happier to see them.
The colony of glow worms in the Wollemi National Park, just a couple of hours north-west of Sydney, was thought to have been destroyed when a bushfire ravaged the area last summer.
The area has been off-limits due to bushfires and heavy rain before the coronavirus pandemic meant NSW's national parks were closed.
Local tourism operator Kristie Kearney was among the first people to return to the tunnel and was relieved to find the creatures safe inside.
"It's nature's Milky Way. It is a celestial experience," she said.
"It's as if you are looking out into the night sky, no moon, and all you see is just these millions of stars on the ceiling."
Ms Kearney grew up in the area and watched in horror as the Gospers Mountain "mega-blaze" — Australia's largest ever bushfire from a single ignition point — raged through the park.
"To be able to see them from one end of the tunnel to the other end was really quite incredible and it was something I hadn't seen in many, many years," she said.
Thomas Ebersoll said he drove up to see if the tunnel had burned before the blaze blocked his access, eventually trapping him at his property.
"You don't see fire, you just see smoke and the odd flare-up burning through that smoke, lighting up the smoke from inside.
"I thought, they are gone, the glow worms are gone," he said.
The University of Queensland's glow worm expert David Merritt said the railway tunnel, with a stream running through the old tracks, had provided the ideal refuge from the fires.
Glow worms are unique to Australia and New Zealand and they date back millions of years.
There are eight known species in Australia and only a handful of places with easy access to the habitats the insects like and where they can be easily seen, such as the Glow Worm Caves at the Gold Coast's Tambourine Mountain and Victoria's Melba Gully.
In Lithgow, you can hike one-and-a-half hours to witness the spectacle of "living light", or you can take an easy 1-kilometre walk from the Glow Worm Tunnel car park — neither require a guide.
Dr Merritt says there is still a lot to learn about the creatures, which are, in fact, fly larvae.
"It's a very unusual mechanism they use to glow, there aren't that many bioluminescent insects, " he said.
