In the moth’s eye, photopigment granules are stored between crystalline cone-shaped structures, or Semper cells, beneath the cornea. Behind that layer, the compound eye of nocturnal insects—defined as a “superposition” eye—has a transparent region called the clear zone. To decrease the brightness of light, the dark pigment is extruded from the cones into the clear zone. Like clouds blocking the sun, the pigment restricts the amount of light reaching the rhabdoms, photoreceptive structures in a layer at the back of the eye. In darkness, the pigment migrates away from the zone back into the cone layer. In effect, the concentration of pigment granules lessens to permit more light and increases to reduce it. (Image by Juliet Percival, originally published in Berry 2022, Environmental Entomology)