Pareidolia: Seeing faces in everyday objects

Leonardo da Vinci wrote about pareidolia as an artistic device. "If you look at any walls spotted with various stains or with a mixture of different kinds of stones, if you are about to invent some scene you will be able to see in it a resemblance to various different landscapes adorned with mountains, rivers, rocks, trees, plains, wide valleys, and various groups of hills," he wrote in a passage in one of his extensive notebooks.