M&M Bulge Illusion
Using Legos and two colors of M&Ms, Mary Coffelt, Briena Heller, and Michael McCamy created the following optical illusion at Martinez-Conde and Macknik Laboratories, Barrow Neurological Institute. The way that the candies are arranged on the checkered Lego pattern, the object appears to bulge even though the surface is flat. This bulge illusion was originally created by Professor Akiyoshi Kitaoka of Ritsumeikan University in Kyoto, Japan.
(via Scientific American)