Iridescence causes surfaces to reflect shifting colors due to light interference. Chemiluminescence produces light via chemical reactions, while bioluminescence does the same in living organisms using luciferin and luciferase. Gemstone colors come from structural elements or impurities affecting light absorption. Mechanical plant defenses include thorns, spines, and microscopic features that help plants survive threats. Režie: Cathy Baker Rok: 2021