Mind-boggling optical illusion challenges you to find the animal hidden among the lines – so what do you see?

A VIRAL optical illusion might leave your head spinning – after all, that’s the easiest way to see it.

Viewers were stunned by the image that conceals a household pet in plain sight.

The tricky image was first shared by Dr Michelle Dickinson, a nanotechnology engineer.

“You can only see this optical illusion if you shake your head,” Dickinson wrote, adding emphasis in parenthesis. “I’m serious.”

At first glance, the striped image is just a series of lines.

You could mistake it for a barcode or TV static without instructions.

But shake your head while viewing the picture, and pointed ears will reveal themselves, along with big, bright eyes.

The hidden image is a black cat starting out from behind the “bars.”

On Twitter, viewers shared their tactics for viewing the confounding image.

“I easily can see it without moving my head, one or both eyes, but it’s more vivid if I shake my head,” one commenter wrote.

“But if I let my eyes rest on it, it melts away after a few seconds,” they added. “Comes back if I refocus.”

The ability to see the image may also depend on which device you’re viewing.

“I can see it without shaking my head on my phone, but I can’t do that on my laptop,” a woman wrote in response.

“Cheat: shaking hand is enough,” another phone-user wrote.

Though the intended image was a cat, others saw different images in the picture.

“Cat or owl?” a viewer asked.

And Dickinson’s friends also engaged in some light teasing – maybe because they felt they looked silly trying to view the image.

“I’m shaking my head AT you,” a playful response read.