What is the optical illusion of the woman in the mirror?

An optical illusion known as "All is Vanity" by artist Charles Allen Gilbert depicts an upper class woman viewing her reflection in a mirror while also presenting an image of a skull. The piece dates back to the year 1892 when it was originally sold to "Life" magazine.

This artistic trick is known as an ambiguous optical illusion in which the viewer can see two distinct images within a single picture. In this particular instance, the rounded top curve of the woman's mirror also serves as the cranium of the skull. The woman's head and hair can also be viewed as the skull's dark eye sockets.