14 brain-teasing pattern puzzles that went viral and stumped the internet

Pattern puzzles are fun to figure out, give your brain a workout, and may even have some cognitive benefit.

They're kind of like optical illusions, in that they trick your eyes to keep the truth hidden from them.

Some extraordinarily well-designed ones have gone viral in the past few years, as well as some accidental ones.

Here are 14 of them that stumped the internet.

Do you see the card among the gift bags?

In a puzzle that went viral in December, a Christmas card was hidden among a set of gift bags. It came from the book "Bear's Merry Book of Hidden Things" by the Hungarian artist Gergely Dudás.

Can you find it?

Here's the solution.

The card was hidden in plain sight in the upper-right of the picture. It's the only rectangular-shaped object without a string.

Seem familiar? That's because the same artist made one with snowmen.

There's a panda hidden among the snowmen in this other Dudás illustration, which went viral in December 2015.