This article is the second in a series in which I am presenting research on some of the more obscure members of our global ecosystem. I believe that by understanding the complexities of our global flora and fauna, we are in a better position to promote respect and conservancy for our natural resources.

     It is clear that our ecosystems are incredibly complex and interwoven. For every small disruption that we make to the health of the planet, there are repercussions to the rest of the ecosystem. And with major disruptions such as climate change, the effects on our ecosystems are unparalleled and potentially catastrophic.

     Hence, in this series, I am asking the question, who is this obscure representative of plant or animal life, and how does he fit into the larger ecosystem that we need to protect? So I turn to the rare and mysterious stromatolite.

     By way of background, the Earth was formed around 4.5 billion years ago, during Hadean time (4.6 to 4 billion years ago). The Archean Eon was from 4 billion to 2.5 billion years ago. During this time period, life first appeared on earth 3.5 billion years ago. The environment was mostly toxic gases, and all life during this period consisted of bacteria.

     Stromatolites are some of the oldest fossils on the planet. What is a stromatolite? Stromatolites are layered, sheet-like, rock-like structures, which contain the fossils showing the presence of ancient bacteria called cyanobacteria. Their colony structures eventually reacted with calcium carbonate in the water to form limestone and create these solid structures. Stromatolites are called ?trace fossils? because they show the presence of the layers of cyanobacteria that lived as colonies of bacteria. Trace fossils are indirect evidence of life such as footprints, burrows, trails and other signs in nature.

     Stromatolites have internal layers and develop upward in columns and domes. These are structures created from the residue of colonies of bacteria. The top surface is a mat of cyanobacteria that traps the sediment that passes through. This mat is where the cyanobacteria live. They survived because there were no animals yet like snails to graze on them. Today, the stromatolite only develops where extreme conditions prevent these grazers, so that only the cyanobacteria survive.

     Cyanobacteria is a single-cell microbe that exists today in environments like lakes and rivers. It has existed since the Archean Eon. Bacteria was the only life on Earth for the first 2 billion years of life. Cyanobacteria are prokaryotic cells, which lack a nucleus. Cyanobacteria are important because they conduct photosynthesis. The spread of cyanobacteria during the Archean Eon meant that photosynthesis began to occur on a massive scale. This changed the environment by releasing free oxygen into it, so that the atmosphere changed to support new forms of life, including the eukaryotic cell.

     Another way that cyanobacteria was important to our planet is that the photosynthesis that occurred helped save our planet from drying up. Because photosynthesis produces oxygen, which combines with hydrogen to form water, this keeps our planet from drying up. Scientists say that without this, our planet would have dried up from escape of hydrogen molecules into the atmosphere (which robs the planet of water from those molecules forever) about 1.5 billion years into the Archean Eon, which they say may be what happened on Venus.This shows the impact of bacteria, and photosynthetic bacteria, like cyanobacteria, on life on Earth.This led to the what is known as the "Great Oxidation Event" that altered the atmosphere to the current oxygen-rich one we take for granted.

     Since stromatolites are not living beings, but rather the housing for cyanobacteria, then the relevant taxonomy is for cyanobacteria:

Domain: Bacteria

Kingdom: Eubacteria

Phylum: Cyanobacteria

     This phylum conducts photosynthesis. "Cyano" comes from the Greek word for blue. They are prokaryotes. Stromatolites have been found as fossils in early Archean rocks, and they increased during the Archean Eon. They declined during the Protozeroic Eon and are not common today. However, they still exist in extreme climates like Sharks Bay, Australia. Cyanobacterial mat mounds are also found at Yellowstone Park in Montana. There they are very small (only a few centimeters across) but their shape is the same as the Sharks Bay mounds.