A puddle of green goop was spotted waiting for the subway at the 34th Street-Herald Square station this morning, but actually it's nothing to worry about, and is in fact the good kind of goop, according to the MTA.

"The color is from a green dye that was placed in the water source in the area to help locate a known water leak in that location," MTA spokesperson Amanda Kwan told Gothamist. "The structure that is above that water leak is a water pipe. It has been cleaned."

Still, it's not every day that a pool of snot-colored liquid with a cloudy hurricane eye appears at your local station. Commuter Nick Caruso, who shared the photo with us, says he was initially worried that the substance was a chemical coolant, but was reassured by the MTA's quick online response.

Dear @mta and @nyc311:



There is green chemical coolant leaking and pooling in the Herald Square station this morning.



Not acceptable. pic.twitter.com/gv984phb0f — Nick Caruso (@thenickcaruso) July 27, 2017

Caruso also said that there were "No smells apparent, beyond the 'usual' subway musk, and at the rate the liquid was dripping, I'd say it had been going since very early this morning, which would mean throughout today's rush hour."

Good thing it's totally harmless green goop and not that radioactive green goop that will spawn a new generation of mutant chihuahua-sized rats with a lust for human toes.

In previous episodes of 'Name Of That Subway Fluid': the blood-soaked newspaper trail on the 7 train, the Airborn Nontoxic Gas Event at Times Square last year, and the great gushing waterfall of the 6 train.

There's also this puddle of green sludge that oozes through the streets of Midtown every so often, which is probably fine, also.