This Mona Lisa knockoff is turning heads in Saint John. (CBC)

An unusual piece of street art in uptown Saint John has people talking.

A Mona Lisa knockoff made out of paper suddenly turned up on a rock wall behind a parking lot near King's Square.

Alison Gayton doesn't know who put the Mona Lisa here. But, as a potter and someone who spends a lot of time around art supplies, she's taking an educated guess about how this DaVinci knockoff was put together.

"They would have painted it on the surface here," said Gayton. "And then put this on in one piece."

The mural comes as a spontaneous surprise, as it seemingly popped up overnight. Some call it an art bomb, a term more often used for graffiti than works by grand masters.

'It's often you see our landscapes enhanced, uh, in other ways. But that was a total pleasure.'—Gina O'Rourke-McKay

"I looked up at the end of the parking lot and it was such a pleasure," said Gina O'Rourke-McKay. "It's often you see our landscapes enhanced, uh, in other ways. But that was a total pleasure. So yeah, keep it up. Bomb us some more."

"I first saw the Mona Lisa in a museum," said Peter Asimakos. "But this one I saw the other morning when I pulled in to park my car and I was pleasantly surprised. This one is quite good. I like the modern take on it, with the nose ring."

Nate Guimond has painted murals on schools and churches in Saint John.

He wishes there was a legitimate interest in commissioning more works of art in the city.

"I think there should be more demand for art in public places," said Guimond. "Where it can access people who don't already have their minds made up. They're still learning about the world."

The piece of art is signed by someone - or some people - who go by the name Tripledog.

Alison Gayton said they have good reason for keeping their secret:

"It's actively frowned upon by many facets of the community and so it would be difficult to come out valuing something that is illegal like this, if say your job is to place value on private property, for instance," said Gayton.

With rain in the forecast, it's not clear how long the paper Mona Lisa will last.