STROMATOLITES

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Picture Courtesy: https://www.businessinsider.in/science/news/the-first-life-forms-on-earth-might-have-come-from-saudi-arabia-scientists-find-new-proof/articleshow/110671214.cms

Context: The discovery of living stromatolites on Sheybarah Island in Saudi Arabia represents a significant breakthrough in our understanding of Earth's ancient history and the evolution of life.

Discovery on Sheybarah Island

• Scientists discovered living stromatolites on Sheybarah Island, located in the Red Sea, dating back 3.48 billion years. This discovery challenges previous assumptions that stromatolites only thrived in select modern environments like Shark Bay, Australia, and the Exuma Islands in the Bahamas.
• The harsh environment of Sheybarah Island, characterized by extreme temperature fluctuations, alternating wet and dry conditions, and nutrient-poor waters, resembles conditions in which stromatolites are known to grow.

Stromatolites

• Stromatolites are layered deposits of limestone, primarily formed by the growth of blue-green algae. These structures are characterized by thin, alternating light and dark layers, which may be flat, hummocky, or dome-shaped.
• They were common in Precambrian time, more than 542 million years ago, and some of the first forms of life on Earth are recorded in rocks 3.5 billion years old.
• Stromatolites grow in greatest abundance in Shark Bay in Western Australia, where evaporation causes high salt concentrations that discourage snails and other organisms from eating the algae.

Great Oxygenation Event

• Stromatolites were instrumental in the Great Oxygenation Event, which occurred over two billion years ago. This event involved the introduction of oxygen into Earth's atmosphere, transforming the planet's habitability and leading to the decline of anaerobic organisms.
• Stromatolites developed in the oxygen-poor environments of the early Earth but declined as other forms of life adapted to the oxygen-rich atmosphere.

Source:

Business Insider

Britannica