A circle, in the centre of a square. But viewed from the other side - or in a mirror - and there are now four circles in the square!
Rotate it back, it again, it is just a single circle, in the centre of a square. However when you look around the edge, there are four half circles and four quarter circles. So in a way, if you add up all the fractions, it is still four circles...
Created by Kokichi Sugihara, a Japanese mathematician and artist known for his three-dimensional optical illusions. His illusions, which often involve videos of three-dimensional objects shown from carefully chosen perspectives, have won a number of awards at the Best Illusion of the Year Contest.
62 x 62mm