Scientists say these tiny alien-like monsters are changing their views on life at the bottom of our deepest oceans.
Polychaetes, or scale worms, have evolved to survive the intense pressures more than 1,000 meters below the water's surface, where the sun's rays never penetrate.
The creatures, which measure little more than two or three centimeters long, form part of an ecosystem that was unknown until 40 years ago.
But since the 1970s, developments in technology have allowed ever deeper exploration of our marine world.
Instead of a barren wasteland, they discovered diverse communities of creatures that live on and around hydrothermal vents.
More popularly know as 'smokers', hydrothermal vents are cracks in the seafloor, usually found around quake zones, volcanoes and the edges of tectonic plates.
They release superheated water and a cocktail of chemicals that provide a home for creatures like the scale worms.
Daniel Desbruyeres, a senior researcher at I'lfremer, the French Research Institute for Exploration of the Sea, said: "The recent discoveries of hydrothermal vents have changed our views of the whole marine realm.
"The deep sea realm is one of the most diverse habitats on Earth, yet our perception of it is still in its infancy."