The key to this scavenging is the highly ordered nature of the thylakoid tissue in the chloroplasts. Normally these stacks of membranes, called grana, in the chloroplasts simply absorb sunlight. But in iridoplasts, the grana are structured to form photonic crystals that modify the incoming light to make it more available for photosynthesis. They do this by being spaced in a way that corresponds to the wavelength of the light they are absorbing. The peaks in the light's waveform match up with the stacked grana, which effectively reduces the velocity of the light, allowing the chloroplast to absorb it more effectively.