Before 1960, the organisms we know today as bacteria were called blue-green algae. They were classified along with the green algae, the red algae, and the brown algae as photosynthetic microbes. It was universally agreed that all of these carried out green plant photosynthesis, fixing CO2 and generating O2 from water. But in the 1960s it became apparent, from new biochemical evidence, that the blue-green algae, unlike the other algae, are really bacteria: they are sensitive to penicillin because of their peptidoglycan cell walls; they have bacterial-sized ribosomes sensitive to the usual antibiotics; and they do not contain organelles such as chloroplasts and mitochondria. A major consequence of the name change was to remove this vast array of organisms from the realm of botany and to put them into the microbial world [http://www.cell.com/current-biology; 04/04/2017].