[Maris]

The phenomenon is para-eidolia or pareidolia. There does not seem to be a consistent spelling.

The basis is though to be the inclination of the human brain to find and remember patterns in nature. Classic examples include people reporting animal shapes in clouds or finding the face of Jesus etched on a half burnt taco.

An intriguing conjecture is that para-eidolia is the exact opposite of seeing. A pattern that exists in the brain is projected onto the world via the lens of the "minds-eye". Another aspect is the tendency of people to see what they expect to see. Think of those honest earnest astronomers who saw the Martian canals, the canals they though were there lurking always at the edge of visibility.

Photography, in its original sense of sensitive surfaces absorbing samples of subject matter, is a powerful anodyne to the tendency of the brain to make thought visible. One could philosophise about astronomers capturing digital images of Mars, finding no certain canals, and PhotoShopping until the darn things were visible even to amateurs.