The Atmosphere

Were you aware that the first production of oxygen in the atmosphere was by the first plant-like form on earth, the Lichen? The Lichen is a composite of a fungus and a cyanobacteria or blue green algae that live in a symbiotic relationship, the fungus harboring and moisture producing while drawing sugar from the algae.  Possibly a paradox like the baby nourishing the nursing mother. The algae, an anaerobe, produces oxygen and sugar by way of photosynthesis, CO2+H2O producing free oxygen that is usable. Moreover the O2 molecule when unstable produced free radical O that combined with O2 to produce O3 (Ozone) a layer that resists ultraviolet rays from the sun that can kill. That the lichen is the first plant-like form on earth is clear from fossil records and the appearance of oxygen seen from ferrous mineral records at the same time, tells us of the importance of this gift that would grow on bare rock and eventually produce the gas of life for the animal world and provide our protection from ultraviolet rays. In 2011 I wrote a poem celebrating the Lichen in my book An Elderly Eclectic Gentleman. I called the poem Succession and will repeat it here since we  owe the Lichen so much. Please bear with me because if the foregoing doesn't thrill you much,  it does me.
The Lichen grows on bare rock,
no earth, little sustenance,
a tenuous foothold to life.
It asks for sun and time
and grows, defeated, grows again.
It rains, it grows, summer drought comes,
it dies, to grow again with rain.
And when it dies it leaves a little behind.
Soil? Or is it the merest memory of Lichen
becoming soil?l
So.Mosses grow, a succession plant,
thicker, greener, richer
because of the poor precursor
which took a foothold where no other could.
  The foregoing tells you that CO2 was drawn from the atmosphere to produce oxygen.
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