Mona Lisa's smile may not be the only enigmatic element to the iconic Leonardo da Vinci portrait.

A graphic designer from Rochester, NY, is claiming that there are hidden images of animals in the masterpiece, including a lion, an ape and a crocodile.

Ron Piccirillo told NBC that he simply used an old artist's trick when he found the buried images - he turned the painting upside down.

How is Piccirillo the first to discover these images in one of the most studied paintings of all time, asked NBC?

I call it an accidental discovery. I'm not sure why I came on this and no one else hasn't, he said.

The first couple of images, I spotted as I was doing research, I took the Mona Lisa and turned it on her side and noticed the ape's face and the lion's head, he said.

Piccirillo found what he believes to be mentions of the animals in da Vinci's own notebooks. These notebooks contain writings from 500 years ago and re-printed for art and history scholars.

We have the nose, the eyes, we have the mouth and the whole ape face is highlighted and it's facing right, Piccirillo said. Over here we're looking at the lion's head which is also facing right. It's in the mountainous area but you can see its nose right here. It's almost roaring it seems to me, its eyes here. And the rest of it highlighted, he points out. So you have the ape's face right here. You have the lion. I call it the roaring lion right here.

The graphic designer cites a passage in da Vinci's writings that describe a serpent gnawing at Mona Lisa's heart. Piccirillo believes this could be the image of a crocodile he found located in Mona Lisa's cleavage.

The crocodile head is behind the Mona Lisa. To the right is the eye, and to the left is the snout, its jaws open.

Art from the Renaissance period is renowned for secret images and meanings. Da Vinci's and Van Gogh's paintings have been studied for years by academics hoping to unveil some astounding mystery.

Piccirillo may have struck historian-gold.

To view the video of Ron Piccirillo's NBC interview, click here.