What appears to be plain sand and silt at first sight is in fact teeming with life: reaching down at least as far as 2500 m below the seafloor lies the deep biosphere, a realm of microorganisms. In spite of the total absence of light, extremely high pressure, and scarce nutrients, microbial cell numbers in the seabed are even higher than in the water above. Their metabolisms are adapted to surviving under such adverse conditions. As layers of sediments are deposited on the seabed, microorganisms might lie dormant for a very long time. But when provided with nutrients, they quickly resume their activity—when a team of scientist took samples from 15-million-year-old sediments to the laboratory, they woke up a variety of oxygen-using bacteria.In the animation, the currents and movements close to the seabed are shown. In a time-lapse, the displacements of sand layers and silt develop into abstract shapes.
Sources: Vuillemin, Aurèle et al., “Archaea dominate oxic subseafloor communities over multimillion-year time scales”, Science Advances, vol 5, issue. 6, (2019).
Jørgensen, Bo Barker and Ian P.G. Marshall, “Slow Microbial Life in the Seabed”, Annual Review of Marine Science, vol. 8, issue. 1, (2016): 311-332.
Inagaki, F. et al, “Exploring deep microbial life in coal-bearing sediment down to ~2.5 km below the ocean floor”, Science, vol 349, issue. 6246, (2015): 420-424.