BLUE-GREEN ALGAE (LIVING). GLOEOCAPSA. CYANOBACTERIA. NITROGEN FIXING. UNICELLULAR CELLS ENCLOSED IN LAYERS. 250X H [Getty Images]

BLUE-GREEN ALGAE (LIVING). GLOEOCAPSA. CYANOBACTERIA. NITROGEN FIXING. UNICELLULAR CELLS ENCLOSED IN LAYERS. 250X H

Photolibrary Ed Reschke