Lost City Of–Microbes
Atlantis of ancient ruins? Not so fast. What divers thought was an ancient Greek metropolis was actually an outgrowth of microbes. The microbes are stated to be methanogens (archaea that convert carbon dioxide and hydrogen into methane) but I think actually they are methane oxidizers. At the bottom of the ocean, methane often arises at cold seeps, places where petroleum components and minerals seep up from subsurface volcanic activity. The minerals get oxidized by bacteria, and carbonates precipitate into odd formations.
Our Gulf of Mexico is full of cold seeps, where the methane gets oxidized by sulfate bacteria, as indicated by isotope ratios. Some of the sulfate bacteria then inhabit clams that may lose their feeding ability. The reduced sulfate can then be oxidized to sulfides within symbiotic worms. Green dots show fluorescently labeled bacteria oxidizing sulfides within the worm. The size bar is 0.02 millimeters.
So indeed, there is a complex intricately cooperative civilization–of microbes. Meanwhile, carbonates precipitate with magnesium ion, forming dolomite. The dolomite formations date to several million years ago–even more ancient than the Greeks. As the authors state, “Exposure on the modern seabed in the shallow subtidal zone has caused confusion, as concretion morphology resembles archaeological stonework of the Hellenic period.”