The key to solving this illusion is not to search for a perfectly detailed animal. Instead, look for subtle differences in shading. The creature is created from very faint shapes that blend into the gray background, so staring too hard can actually make the image more difficult to interpret.

Focus near the center-right portion of the circle. You may first notice a rounded shape that looks like a head. Just ahead of it is a protruding curve that begins to resemble a snout. Above that sits another faint curve, which forms the animal’s ear.

Now look lower in the image and you may be able to make out the suggestion of legs beneath the body. Put those features together and the answer becomes much clearer. Think of a farm animal famous for rolling in mud and making an unmistakable “oink” sound.

The hidden animal is a pig. Once your brain recognizes the shape, the illusion changes completely and the pig becomes much easier to see. That is what makes these visual challenges so entertaining: nothing in the image actually changes, but your perception does. If you spotted the pig before reaching the answer, you passed the challenge. If not, look again now—you may wonder how you missed it the first time.