From Microbes to Cell Giants - Animate Earth: Science, Intuition and Gaia - page 140

synthetic cyanobacteria to abundantly populate many parts of the globe. Photosynthesis
as we commonly know it had arrived, and has remained the major biological fixer of the
sun's energy for the last 3,500 million years. The early alchemists had a great name for
it; observing how green plants drink in sunshine, and sensing its power, they called it
'Green Lion Eating Sunlight'.
Figure 34: Gomphosphaeria sp., a modern cyanobacterium,from Laguna Figueroa, Baja Califor-
nia Norte, Mexico.( photo © Lynn Margulis )
Some of the earliest photosynthetic bacteria lived in large colonies. Under the bright
blue skies of Western Australia, in a place called Shark Bay, peculiar metre-high mounds
litter the beach and foreshore like overgrown potatoes poking up through the sand ( Fig-
ure 35 ) . These are stromatolites— rock-forming communities of bacteria which were
common all over the planet soon after life began about 3,500 million years ago. Mostly,
each mound is a dome of rock, but on its top perches a cyan-coloured film of slime
where the microbes live. Here, many species cohabit, each contributing to a veritable
bacterial community as complex and communicative as any human city. Looking care-
fully, on top of a single dome we see silver bubbles appearing on its slimy surface. Some
bubbles have already detached like miniature hot air balloons, and are dissolving in the
crystal clear water. Freshly minted oxygen, made just as it has been for the last 3,500
million years, enters the atmosphere, energising the whole of Gaia. The bacterial com-
munity also creates the rocky dome on which it perches, either by secreting mucus that
binds and lithifies particles of sediment, or by the direct precipitation of calcium car-
bonate. The bacteria constantly move towards the light at the top of their mound as it