From the 'man in the moon' to Jesus on a piece of toast, humans see faces in all sorts of objects.
A new study in Australia has delved deeper into the phenomenon, known as face pareidolia, and found it's a key part of our survival mechanism.
"We need to read the identity of the face and discern its expression. Are they a friend or a foe? Are they happy, sad, angry, pained?" says Professor David Alais.
He's led the University of Sydney study that looks at how the brain processes real and imagined faces.
It turns out they're the same function, happening in a few hundred milliseconds.
"From an evolutionary perspective, it seems that the benefit of never missing a face far outweighs the errors where inanimate objects are seen as faces," Prof Alais said.
"We know these objects are not truly faces, yet the perception of a face lingers.
"We end up with something strange: a parallel experience that it is both a compelling face and an object. Two things at once."
It's so hard-wired that the brain has specialised neural mechanisms to rapidly detect faces.
The research, published on Wednesday in the Proceedings of the Royal Society B, looked at what happens in the brain once a pareidolia face is detected.
It found once a false face is "seen", it is analysed for its expression in the same way as if it's a real face.
"When objects look compellingly face-like, it is more than an interpretation - they really are driving your brain's face detection network," Prof Alais said.
"And that scowl, or smile: that's your brain's facial expression system at work. For the brain, fake or real, faces are all processed the same way."
The study was a collaboration with the Laboratory of Brain and Cognition at the National Institute of Mental Health in the United States.
