Sir Roger Penrose standing on a floor with a Penrose tiling in the foyer of the Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, US, in 2010. Penrose is also widely known for his work in general relativity and cosmology, and in 1988 he shared the Wolf Prize for Physics with Stephen Hawking for their Penrose-Hawking singularity theorems. Photo: https://en.wikipedia.org/wiki/Penrose_tiling . The two designs on the right show two tessellations by M.C. Escher. The top one, featuring lizards, appeared first in the 1939 work entitled Study of Regular Division of the Plane with Reptiles, whereas the bottom one, entitled Horeseman (1946), is probably one of Escher’s most attractive and ingenious works. Photo: © M.C. Escher (Source: http://www.pleacher.com/mp/mlessons/calculus/escher.html )