Blue is an elusive color. Crush the feathers of a blue jay or the wings of a Morpho butterfly and you’ll see gray dust; our perception of their electric blue hue depends on microscopic structural features that bend the light just so. The blue sky is merely a mirage of refracting light, as are blue eyes. Truly blue pigments are exceedingly rare in the natural world, which is perhaps part of their allure—blue is our favorite color, according to an international, cross-cultural survey.
If imitation is the sincerest form of flattery, humans have been buttering up the natural world for a long time. It’s often called biomimicry. Think Olympic swimmers in sharkskin-inspired suits, bullet trains shaped like kingfisher beaks, or the ubiquitous Velcro, which was famously modeled after plant burrs.
Yet all of these examples depend on man-made materials and processes. What if we took biomimicry one step further and learned how to grow structures the way they grow in nature?