These unique structures excel at capturing light. When light hits a normal feather, it finds a series of horizontal surfaces, and can easily bounce off. But when light hits a super-black feather, it finds a tangled mess of mostly vertical surfaces. Instead of being reflected away, it bounces repeatedly between the barbules and their spikes. With each bounce, a little more of it gets absorbed. Light loses itself within the feathers.

McCoy and her colleagues, including Teresa Feo from the National Museum of Natural History, showed that this light-trapping nanotechnology can absorb up to 99.95 percent of incoming light. That’s between 10 and 100 times better than the feathers of most other black birds, like crows or blackbirds. It’s also only just short of the blackest materials that humans have designed. Vantablack, an eerily black substance produced by the British company Surrey Nanosystems, can absorb 99.965 percent of incoming light. It consists of a forest of vertical carbon nanotubes that are “grown” at more than 750 degrees Fahrenheit. The birds-of-paradise mass-produce similar forests, using only biological materials, at body temperature.

Vantablack is genuinely amazing: It’s so good at absorbing light that if you move a laser onto it, the red dot disappears. But McCoy has created a similar demonstration with her super-black feathers. In the image below, you can see two feathers, both of which have been sprinkled with gold dust. The left one is from the lesser melampitta—a bird of average blackness—and it looks as golden as its surroundings. The right one comes from a paradise riflebird—one of the 42 species of bird-of-paradise. Yes, it is covered in gold dust. And yes, it still looks black. The gold settles within the grooves of microscopic forest, and all of its glitter is lost.

This opens up several other questions, says Rafael Maia from Columbia University, who studies the evolution of bird colors. “Is this something unique to birds-of-paradise, or have other species evolved similar optical solutions?” he says. “If they have, do they use the same type of feather modifications?”

Many animals and plants use microscopic structures to produce exceptionally vivid colors with metallic sheens; this is called iridescence. Comparably fewer species use microscopic structures for the opposite purpose: to absorb colors entirely. These include a few butterflies and the Gaboon viper.

The viper—whose fangs, at two inches, are the longest of any snake—likely uses its super-black scales for camouflage, breaking up its outline so that the rest of its body better blends into the leaf litter of a rainforest. The birds-of-paradise, meanwhile, probably use their unfeasibly black blacks for the same thing that seems to motivate everything about them: sex.