Pareidolia is the phenomenon of perceiving other things in objects, such as seeing human faces or animal heads in stones. A well-known example of this is the Face on Mars, which is also referred to as the Cydonia Face, named after the region on Mars where it is located. Pareidolia is a misinterpretation of objects caused by the brain, which alters them according to its own perceptions or completes them into something familiar. Over the course of a year, Swiss painter and writer Jean Willi photographed stones that resemble faces, discovering a realm of stones that seems to be teeming with petrified souls. Often, it is the position of the sun that shapes a face and makes it invisible again with a change in light. Sometimes, it is merely two dark spots that the observer recognizes as eyes, transforming them into a face.