What is "pareidolia"

n. The tendency to interpret a vague stimulus as something known to the observer, such as interpreting marks on Mars as canals, seeing shapes in clouds, or hearing hidden messages in music.

Pareidolia is a psychological phenomenon involving a stimulus (an image or a sound) wherein the mind perceives a familiar pattern of something where none actually exists.

Common examples are perceived images of animals, faces, or objects in cloud formations, the man in the moon, the moon rabbit, and hidden messages within recorded music played in reverse or at higher- or lower-than-normal speeds.