Pareidolia

Pareidolia (/pærᵻˈdoʊliə/ parr-i-DOH-lee-ə) 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.