Chemosynthesis is a process of producing energy by burning chemicals.
It requires no sunlight and is typical for deep sea ecosystems near the hydrothermal vents.
It was first discovered in 1890 by Sergei Nikolaevich Vinogradskii as a result of his physiological research in that period. The existence of chemosynthesis was confirmed about 90 years later with the discovery of deep sea hydrothermal vents.
The process itself has some similarity with the photosynthesys, except for the fact that no sunlight is required as mentioned beforehand.
Creatures that use it are able to survive in some of the most extreme conditions on Earth, such as the deep sea scaled worm, which is often considered as a certain link with alien life forms.
These organisms also provide the foundation for further development of the ecosystem as they are hunted by larger creatures.