Nope, these shimmering balls are not your artificial Christmas balls; they are fruits, real fruits (the shiniest in the world) of the plant Pollia condensata.
This berry-like fruit has a special trick to produce its iridescence since it contains no blue pigment at all. It reflects light and colors with exceptional intensity through specially arranged layers of cells. Pollia‘s secret was discovered by Silvia Vignolini from the University of Cambridge, and her group by looking at the plant’s sample under the microscope. The sample was gathered from Ghana in 1974 but has retained its vividness. Unlike pigments, structural colors don’t deteriorate so the fruits stay vibrant for many years Some fossils still keep their iridescence.
The fruit’s outer part has three to four layers of cells, each containing more layers of cellulose fibers arranged parallel but somehow rotated to one another producing a spiral. Some of the light that hits the top layer gets reflected while some passes through. This also happens at the next layers and so forth, with the reflected beams of light amplifying each other to create remarkably vivid colors. The technical term is “multilayer interference”. Or alternatively: “Ooh, shiny!”
Don’t be fooled, however; this fruit’s beauty is only skin deep. It offers little nourishment, if any, because it contains many seeds. Since it grows alongside a plant that produces blue berries, it appears that its characteristically shiny fruit is a means to compete with the other plant and attract birds to pick its fruits instead to ensure propagation.
Read more: The world’s shiniest living thing is an African fruit that looks like a pointillist bauble at Not Exactly Rocket Science
The journal reference: Vignolini, S., Rudall, P.J., Rowland, A.V., Reed, A., Moyroud, E., Faden, R.B., … & Steiner, U. (2012). Pointillist structural color in Pollia fruit. PNAS, 1-4.