Chlorophylls are not the only photosynthetic pigments. Chlorophyll is the most common, but there are also carotene, xanthophylls, pheophytins. They differ from chlorophyll in a light spectrum they absorb. It is known that chlorophyll absorbs red light and reflects green. That's why plants containing chlorophyll are green. However, at a depth of the sea where some plants live, there is no red light but some other light spectrum is present. Plants living in such conditions contain pigments able to absorb available light.