
Image caption
Ancestors of modern cyanobacteria (blue-green algae) may have been the first oxygen producers on planet Earth, and ushered in significant changes in climate. CC license by Flickr user Richard Droker.
Ancestors of modern cyanobacteria (blue-green algae) may have been the first oxygen producers on planet Earth, and ushered in significant changes in climate. CC license by Flickr user Richard Droker.