What is found in Prochlorococcus and essential for photosynthesis?
Prochlorococcus: Prochlorococcus is a genus of very small (0.6 µm) marine cyanobacteria with an unusual pigmentation (chlorophyll "a2" and "b2"). Chlorophyll:  Chlorophyll is essential in photosynthesis, allowing plants to absorb energy from light.
Chlorophyll