Marble Berry is a perennial with hard, dry, shiny, round, metallic blue fruit. It is found in Africa. The blue color of the fruit, created by structural coloration, is the most intense of any known biological material. The surface of this fruit has an especially smooth and transparent outer skin which reflects light like a mirror. Beneath this glossy surface lies a special layer of cells which have an elaborate but unpigmented microstructure, whose function is to reflect light within a narrow range of wavelengths. This structural coloration is created by Bragg reflection from spirally stacked cellulose microfibrils in the walls of these cells. The wavelength reflected depends on the height of the stack, which varies from cell to cell. Variability in the stack height allows more overall light to be reflected and this further enhances the glossy appearance, but it makes the fruit appear somewhat pixelated. Because the berries coloration is structurally derived, even in the dried pictured specimen their luster is unsubdued.