Deep-sea hot springs | AMNH https://www.amnh.org/exhibitions/permanent/planet-earth/why-is-the-earth-habitable/life-that-lives-off-the-earth-s-energy/deep-sea-hot-springs
Driven by heat from molten rock, the entire ocean circulates every one to ten million years through the crust along the mid-ocean ridges.
Cross Section Tree Core Coral Skeleton Wind-carved