Cosmic Science ; = Origin of Life =( Stromatolites )

In 1961 scientists got a real surprise with the discovery of a community of living stromatolites at Shark Bay ...in Australia............. They are lusterless and gray and look like very large cow- pots. you are `yourself staring at living remnants of Earth as it was 3.5 billion years ago. The base, these dull rocks swarm with life ....with an estimated 3 billion individual organisms on every sq. yd of rock. ...you can see tiny bubbles rising to the surface as they give up their oxygen.. In 2 billion years such tiny exertions raised the level of oxygen in Earth`s atmosphere to 20% preparing the way for next, more complex chapter in life`s history. ( Ref - Bill Bryson ; the rise of life,= A short history of nearly everything)