The eggs of the tinamou, known colloquially as the "mountain hen," are a shiny, iridescent, and beautiful blue. And that color is all natural!
A new study in the Journal of the Royal Society interface came to the conclusion that the bird's eggs are officially the first known naturally iridescent eggs.
Discovery News explains that not all color is pigment based — the iridescence is also the result of the way the eggs reflect light depending on the angle they're viewed from. When the researchers removed the eggs' cuticles, the eggs lost the iridescence but maintained a background coloration, implying that the eggs' appearance is due to both pigments and iridescence.
The scientists suggest that the eggs' unique appearance is more than just aesthetically pleasing — it also may help the birds find their eggs more easily and differentiate between ones from different mothers. The researchers also speculate that the egg shells' reflective surface could protect the embryos from solar radiation. Pretty and useful!