Undercarriage of the Mars rover Curiosity.
Curiosity’s arm cam.
Date: 09.11.2012
The fruit from the African plant Pollia condensata is shiny like a Christmas tree ornament. It acheives this brilliant coloring because its cells have a spiralled arrangement that reflects light. The berries are the shiniest living things on the planet.
As explained by Ed Yong:
Under the microscope, Vignolini saw that the outer part of the fruit consists of three to four layers of thick-walled cells (labelled “1″ in the image below). Each cell contains yet more layers, made of cellulose fibres. The fibres all run parallel to one another, but each layer is slightly rotated against the one above it, producing an elegant spiral.
As light hits the top layer, some gets reflected and the rest passes through. The same thing happens at the next layer, and the next, and so on. Provided the layers are exactly the right distance apart, the reflected beams of light amplify each other to produce exceptionally strong colours. The technical term is “multilayer interference”. Or alternatively: “Ooh, shiny!”
Read more about this fascinating berry at PNAS.