Here’s an image of an underwater landscape, with the shallow Bahama Banks fading away into the massive 2000m (6600ft) deep Tongue of the Ocean (TOTO) trench. A combination of currents and drifting sand (and oolitic limestone) paint the iris texture in the transition slope. It is thought that this tropical coral ecosystem is is fertilized by Saharan sands, blown through the atmosphere and across the Atlantic. This contributes to the productive aquatic growth that eventually allows for the formation of fossilized coral foundations and oolitic sands that today have built up to be nearly 4.5km thick.

Stitched Sentinel-2 data from March 26, 2019.

Satellite data from ESA’s Copernicus program. CC BY-SA 3.0 IGO.