Margaritaria nobilis, also known as bastard hogberry, is a fruit-bearing plant found in Mexico, Central America, South America, and the West Indies.The fruit is a bright iridescent blue color, resulting from a complex surface structure which interferes with light waves.
http://www.ecouterre.com/inspired-by-bastard-hogberry-fruit-new-fiber-changes-color-when-stretched/ 'uses' for Margaritaria Nobilis
https://web.archive.org/web/20130409183448/https://www.seas.harvard.edu/news-events/press-releases/bioinspired-fibers-change-color-when-stretched/ ...