<P> Stromatolites (/ stroʊˈmætəlaɪts, strə - /) or stromatoliths (from Greek στρῶμα strōma "layer, stratum" (GEN στρώματος strōmatos), and λίθος lithos "rock") are layered mounds, columns, and sheet - like sedimentary rocks that were originally formed by the growth of layer upon layer of cyanobacteria, a single - celled photosynthesizing microbe . Fossilized stromatolites, some of which may date from 3.7 billion years ago, provide records of ancient life on Earth . Lichen stromatolites are a proposed mechanism of formation of some kinds of layered rock structure that are formed above water, where rock meets air, by repeated colonization of the rock by endolithic lichens . </P> <P> Stromatolites are layered bio-chemical accretionary structures formed in shallow water by the trapping, binding and cementation of sedimentary grains by biofilms (microbial mats) of microorganisms, especially cyanobacteria . They exhibit a variety of forms and structures, or morphologies, including conical, stratiform, branching, domal, and columnar types . Stromatolites occur widely in the fossil record of the Precambrian, but are rare today . Very few ancient stromatolites contain fossilized microbes . While features of some stromatolites are suggestive of biological activity, others possess features that are more consistent with abiotic (non-biological) precipitation . Finding reliable ways to distinguish between biologically formed and abiotic stromatolites is an active area of research in geology . </P>

Stromatolites found in western australia are are produced by which organism