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.
Pareidolia 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.
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.
Images for kids
The Jurist by Giuseppe Arcimboldo, 1566. What appears to be his face is a collection of fish and poultry.
Map of Martian "canals" by Percival Lowell
Given an image of jellyfish swimming, the DeepDream program can be encouraged to "see" dogs