Cyanobacteria

Phosphorus provides nourishment for cyanobacteria (blue algae) which multiply and release toxins.

Source: tatoeba (501178)

Stromatolites are the limestone structures formed by photosynthesizing bacteria called cyanobacteria. They created layers of alternating slimy bacteria and sediment in very shallow water, dominating shallow seas until predators, such as trilobites, came into the picture.

Source: tatoeba (6920722)

Emergency water rescuers told vacationers on hot, sandy beaches—from Swinoujscie in the west to Gdynia in the east—not to enter the sea, where thick, green-brown cyanobacteria colonies have grown and pose a health threat.

Source: tatoeba (7043636)

Then about 2.3 to 2.5 billion years ago, during the Proterozoic Eon, blue-green algae called cyanobacteria, living in Earth’s shallow oceans, began emitting enough oxygen through photosynthesis to create the permanently oxygenated atmosphere that keeps us alive today.

Source: tatoeba (11119114)