Very few ancient stromatolites contain fossilized microbes. They close with lacustrine limestones containing stromatolites, charophytes, and ostracods. Fossilized stromatolites provide records of ancient life on Earth. Fossilized stromatolites are found in the Galeros. The earliest complex trace fossils, not including microbial traces such as stromatolites, date to . Fossils of stromatolites and algae are found in this layer. Among the oldest remnants of oxygen-producing lifeforms are fossil stromatolites. Much of the fossilized stromatolites of the world can be found in Western Australia. In the proximal sections, the formation comprises limestones of stromatolites and laminated microbialites. The grain size of sediment portion of stromatolites is affected by the depositional environment. These laminations can accrete over time, resulting in the banded pattern common to stromatolites. The earliest stromatolites are found in 3.48 billion-year-old sandstone discovered in Western Australia. In the lowest Cambrian, the stromatolites were decimated. Additionally, giant stromatolites are found off the Exuma Cays. It is hypothesized that some stromatolites contain a new form of chlorophyll, chlorophyll f.