Deep Ocean Vent

The deep ocean vents are contain many geothermal vents. These sulfur spewing chimneys are known as "black smokers". They form when the heat of the magma comes through the planet's crust. This creates superheated water which is rich with minerals. These minerals (mostly sulfur) crystallize to make the chimney-like shell. The reason it has black smoke is when the minerals hit the cold water they harden and appear black. These minerals become the main energy source for the deep ocean vents ecosystem.