Strelley Pool Stromatolite: Archean Age (3.4 Billion years ago), from Strelley Pool Formation, Pilbara, Western Australia, polished slice, 234g, about 19 x 10 cm, a beautiful specimen with its yellow colour. [The Strelley Pool Formation preserves an environment that existed 3.43 Billion years ago including the first signs of life in several kinds of fossils known as stromatolites]