Authors: Andrew W. Piotrowski, Gideon Paul Caplovitz

Country: USA

Description: Triangles may be simple shapes, but in certain configurations they are truly amazing! Here, a large red triangle is partially covered by six smaller black triangles all lying flat in the two-dimensional plane. With little effort, one can almost feel the brain re-organize this visual input into a three-dimensional experience of a red ‘propeller’-like shape in front of a black box. The box has gaps along its edges and if you look closely, you’ll see something in the box! The straight edges of the triangles give rise to curvature. What is it? What is in the box? It’s a circle!