Galápagos hydrothermal vents (1977)
Scientists in the submersible Alvin found hydrothermal vents on the Galápagos Rift. Tube worms, clams, and bacteria thrived in water over 350°C, in total darkness, running on chemicals from the Earth's interior instead of sunlight.
Proved ecosystems can run on chemosynthesis, not sunlight.
Made subsurface oceans on other worlds plausible habitats for life and reshaped astrobiology's core assumptions.
Ocean worlds have no sunlight reaching their seas. The vent discovery showed sunlight is not a requirement for life.
