Even the smallest organism can have a major influence on the evolution of life on Earth. Microscopic algae that inhabit the sunlit waters of the ocean surface are not only responsible for about half of the photosynthesis on the planet but are also valuable as a nutrient-rich food source sustaining the entire marine ecosystem. In their recently published study, Prof. Itay Halevy and Dr. Shlomit Sharoni from the Weizmann Institute of Science’s Earth and Planetary Sciences Department reveal the processes that made these miniscule organisms such a good source of nutrition for others higher up the food chain – and how this in turn advanced evolutionary change over the past half a billion years.