A hole opens up in the street and a fluorescent green fluid appears inside.

What is that stuff?

It sounds like a scene from an episode of "The Teenage Mutant Ninja Turtles," a Nickelodeon slime show or a toxic waste dump.

But this isn’t science fiction, this sinkhole filled with fluorescent green goo is reality and it’s located on a Philadelphia street. Steven Reitz can prove it. The Northern Liberties resident shot a photo of the "radioactive-looking" sinkhole along Randolph Street near Girard Avenue last week.

Reitz’s photo was then shared around the world after he posted it to the social discussion site, Reddit. Since then, hundreds of Reddit users weighed in on what exactly was the green liquid in the sinkhole. More than a few mentioned the Ninja Turtles as a possibility.

There would be no “Splinter” in this story however, even if there was still a mystery.

It seems the mystery of what caused the bright green water and who was responsible might be answered by Philadelphia Gas Works -- since their name "PGW" is stamped on the traffic barricade -- or the Streets Department -- since this is a hole in the street – but a few phone calls revealed that the radioactive-looking water came from the Philadelphia Water Department.

Philadelphia Water Department spokeswoman Laura Copeland tells NBC10.com that the green-looking fluid is actually a “safe, non-toxic and biodegradable” dye used as a tracer. It helps workers identify the cause of sinkholes, cave-ins and other holes in the ground.

“Since most of our infrastructure is outside, we mainly use the green dye as it is the most visible and can be seen at the greatest distance in our infrastructure,” Copeland said. “

Green is not the only hue on the palette of problem-solving colors. They also use blue and red dyes to differentiate other sources of a break, especially when working inside a home, Copeland said.

The colored water doesn't pose a threat to the general public, according to officials.

And that gaping hole in the street?

Soon after posting the photo, Reitz reported back that the hole was already boarded over.