Pareidolia

Pareidolia /pærɪˈdoʊliə/ parr-i-DOH-lee-ə) is a word from Ancient Greek to describe the phenomenon, that the human mind often perceives familiar patterns in a stimulus, even when they are not there.

Satellite photo of a mesa in the Cydonia region of Mars, often called the "Face on Mars". This was given as evidence of extraterrestrial habitation. Later higher-resolution photos from other viewpoints demonstrated that the "face" is in fact a natural rock formation.

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.

Pareidolia is a special case of clustering illusion.