David Attenborough began his extraordinary tv series, The Living Planet at Shark Bay in Australia's northwest, because crossing the low dunes and descending to the beach is like slipping billions of years back in time. Where the waves gently break on the shore are stromatolites, rising like rows of concrete cauliflowers from the ocean. While they may look like inanimate rocks, examining a piece from the surface under a powerful microscope shows that it is teeming with life. Stromatolites are complex domes or columns of sediment formed by microbiological communities. These 'living rocks', as th |