She took it to the Special Slimes Investigations Unit.

A homeowner left internet users both horrified and perplexed after sharing photos of a nightmarish black mass lurking beneath her friend’s floorboards in Melbourne, Australia.

According to Yahoo News, the woman, named Hannah Sycamore, had learned of the sinister-looking slime from a pal, who had stumbled upon it while ripping out her floorboards.

Hoping to unravel the creepy caper, she uploaded the spine-tingling images to the Australian fungus group on Facebook with the query, “Any ideas what this is?”

Accompanying photos show the mystery ooze, whose dark tendrils are spiderwebbed across the floor like a malevolent presence from some Japanese horror film.

Facebook commenters had several theories on the identity of fungal fractals, which had even stalwart Aussies heading for the hills.

“The veins of ‘nooope’,” quipped one Facebook wit.

Others compared the tendrils to the Mind Flayer, the undulating tentacle monster from the hit Netflix series “Stranger Things.” Some online comedians joked that it was the alien symbiote “Venom” from the Marvel movies.

Meanwhile, some mycology buffs said the ooze could be either slime mold, tree roots or black mold, an insidious fungus that has been associated with a number of health concerns including breathing problems and dementia.

“Not a slime mold. A black mold is possible,” postulated Adam Labrock, the “Head Fun Guy” at the Mushroom Co, an urban fungus farm in New Zealand.

He then speculated that Armillaria (honey fungi), which often grows along tree roots, had spread beyond its host and then infiltrated the domicile.

“It’s probably something you need to get a structural engineer to look at,” Labrock concluded.

Other experts were similarly flummoxed, positing a similar theory.

“It’s a new one to me too,” an unidentified scientist from the state herbarium in Brisbane told Yahoo News. “Certainly doesn’t look like traditional mold.”

They, too, surmised that the mystery mass could be Armillaria, but wagered that was a long shot.

This isn’t the first time a fungal-looking anomaly has reared its head Down Under.

In March, an Australian town resembled the set of HBO‘s dystopian horror series “The Last of Us” after a mysterious red mass sprouted up under a fire hydrant — and eventually “climbed up the water spout.”