Researchers made nano-sized balls of melanin aggregate into clusters called supraballs. Melanin appears black in individual nanoparticles. But altering spacing of the nanoparticles in the ball affects how the particles scatter light. A thin silica coating on the outside of melanin nanoparticles acts like a bumper, limiting how close the particles can pack together. Varying the diameter of the melanin core and the thickness of the silica shell creates supraballs in a range of colors.