Iridophores, sometimes also called guanophores, are pigment cells that reflect light using plates of crystalline chemochromes made from guanine. When illuminated they generate iridescent colours because of the diffraction of light within the stacked plates.
Orientation of the schemochrome determines the nature of the colour observed. By using biochromes as coloured filters, iridophores create an optical effect known as Tyndall or Rayleigh scattering, producing bright-blue or -green colours.
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