It looks like a series of black and white lines.

But in reality, there's an image of an animal buried under the latest optical illusion sweeping social media. The image was first shared online by New Zealand-based nanotech engineer, Dr Michelle Dickinson. Alongside a crying-while-laughing emoji, she wrote:

"You can only see this optical illusion if you shake your head (I'm serious)."

If you're having trouble seeing the critter, try taking a step away from the screen - whether that means from the computer or holding your phone a bit further away.

You can only see this optical illusion if you shake your head (I’m serious) ? pic.twitter.com/WhtZ1b0r4t

— Dr Michelle Dickinson (@medickinson) January 10, 2019

Alternatively, you can shake your phone. That seems to be working pretty well for people, too. Tilting the screen slightly, if you're using a laptop, may also cause the animal to appear. A few social media users have claimed they were able to see the animal straight off the bat, without having to shake their head. Many others, though, took to the comments to share their own methods of solving the illusion.

I can easily see it without moving anything.

— Zemzy Oseris (@officialzemzyt) January 12, 2019

I can easily see it without moving anything.

— Zemzy Oseris (@officialzemzyt) January 12, 2019

I can easily see it without moving anything.

— Zemzy Oseris (@officialzemzyt) January 12, 2019

I can easily see it without moving anything.

— Zemzy Oseris (@officialzemzyt) January 12, 2019

We don't want to spoil the riddle - so, if you still can't find the animal, just take a scroll through the replies to the original tweet. The responses will definitely help.