Pareidolia is something that’s very common. So common, in fact, that you’ve probably seen countless examples of it. You knew what it was even if you didn’t know what it was called. Pareidolia is a type of false perception that helps us make sense of the world. It happens when our brains organise the completely random patterns seen by our eyes into things we can identify. This is why and indeed, how we “see” dragons in clouds, a man’s face on the Moon, and why the random burn marks on a grilled-cheese sandwich or a tortilla seem to resemble the Virgin Mary.
This is not something over which we have any control. Our brains are wired for it. Personally, I think it’s kind of weird and wonderful that we “see” human faces and familiar forms everywhere, but I’m left guessing as to the biological or evolutionary purpose of this ability. I’d like to think that there’s a reason for it but maybe it’s just a fluke. Still, it does provide a lot of entertainment value, particularly when people associate the things they think they see with the religious or the sacred. And it happens all the time. Here is a page from teh intarwebz with tons of examples. Some of them are pretty convincing, but others are really stretching it.
Finally here’s a very old photograph with some of the best pareidolia I’ve ever seen. The image of a Jesus-like face can clearly be seen next to the figure of the man in the middle left of the photograph. Look again and you’ll see that it’s actually a little girl sitting in her father’s lap.
Neat, huh?
Random Misanthrope 
Probably also the reason I saw evil elves on the patterned curtains in my bedroom when I was a child.
I confess that I had never heard the actual term until you first used it after my recent pareidolian experience. (That is opposed to pareidoilyan – the phenomenon where you think you see crocheted doilies everywhere…..)
A good reason why you had not heard of the word pareidolia could be that it was never used before 1994. Wordspy says it was first used by Steven Goldstein to describe an error in perception, despite the resemblance actually existing. The fact is, the recognition of a resemblance has been happening since the beginning of time and has had many vocabulary words invented in its honor such as apophenia, simulacra, patternicity, paranoiac-critical method, the cozen’s method, and anthropomorphism to name a few. I use the word Extractionism and its the technique I used to discover my character the Old Man in the Peanut.
Definitely took a minute for me to see the little girl, and not the Jesus face. These sort of things are why I got into Psychology to begin with. Very interesting.
Quite amazing.