Humans have a remarkable ability to connect dots, extrapolate lines and build mental images of the world through vision. Faster than thought, most of the time.
Those features aren’t just ancient evolutionary facts from millions of years ago, they still work today. Sometimes the images appear fast, sometimes it takes a moment or two to have the brain connect.

This, spotted on a t-shirt. Took my brain a little too long to “see” image and ask for a photo.
Can you spot the animal that isn’t really there?