This object is known as a type of anamorphic painting or a turning picture. The viewer is initially confronted by a distorted perspective caused by two images painted on alternate sides of vertical strips. The images - a young woman (previously thought to be Mary, Queen of Scots) and a skull - can only be seen in their true form from a single viewpoint. This suggests that the painting was probably created as a private momento mori ? a reminder of death. The painting should be looked at from left to right to reveal the human head changing into a skull.