Pareidolia is a type of illusion or misperception involving a vague or obscure stimulus being percieved as something clear and distinct. This happens a lot with people saying that they see a face in many different things like trees, clouds, pictures, and many other things.
You may see a face of a bearded man, but it is really just a child sitting on the mans knee, with a hat on.
This is a picture of a crater on an asteroid.
This also may look like a face, but it is actually just the shadow of the crater's rim cast by the distant sun.
This is the grilled cheese sandwich that people see the Virgin Mary's face. It was put up on eBay and bought for $28,000.