What do you see? A vase or 2 faces?
This is the illusion of the Vase or Rubin's Cup, one of the most famous optical illusions in the world.
In this illusion you can perceive the figure and the background in an alternative way. By focusing your gaze on the black area you can clearly see the vase. In turn, when viewing the white area as a background, the faces become the central figure.
What do you see?