Retinal photosynthesis, also known as the Purple Earth Theory. Colours are weird. Earth plants absorb red and blue light, they look green to us because that’s the wavelength of light that cannot be used by the chloroplasts. It’s hypothesized that this was advantageous on Earth because blue light goes further into water than the other wavelengths, facilitating the development of photosynthetic algae

Retinal photosynthesis is another viable chemical chain reaction that could be used to create ATP (usable biological energy) from light. It’s another molecule similar to chlorophyll, but it absorbs green light instead of red/blue - alien planets might be purple! There’s an viable parallel evolutionary pathway that leads to plants with magenta leaves