Stromatolites Powerpoint slides: Images from visiting Shark Bay World Heritage Site, Western Australia. 'Stromatolites or stromatoliths 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 provide records of ancient life on Earth. Stromatolites are a major constituent of the fossil record of the first forms of life on earth. They peaked about 1.25 billion years ago and subsequently declined in abundance and diversity, so that by the start of the Cambrian they had fallen to 20% of their peak. The most widely supported explanation is that stromatolite builders fell victim to grazing creatures (the Cambrian substrate revolution); this theory implies that sufficiently complex organisms were common over 1 billion years ago. Another hypothesis is that protozoans like the foraminifera were responsible for the decline. (Source - Wikipedia);
Royalty-free music: "Wind Swept" Kevin MacLeod (incompetech.com)
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Негізгі бет Ғылым және технология Stramatolites, Shark Bay, Australia -
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