Twelve species new to science were discovered deep in the Atlantic after five years of study by the ATLAS Project.
Scientists have discovered 12 new species from the lowest depths of the Atlantic Ocean.
Researchers say the sea mosses, molluscs and corals have previously gone undetected because so much of the seafloor has yet to be explored.
The species live up to 400 metres below the surface of the oceans on black corals.
The team from the EU-funded Atlas Project also said that it found dozens of species in areas where they were previously not known to exist.
But the new discoveries may already be under threat from climate change.
As more carbon dioxide is absorbed by the planet's oceans - the waters become more acidic, threatening the species habitats.
University of Edinburgh Professor Murray Roberts, who led the project, told Euronews that these creatures are associated with deepwater corals and also with sponge grounds. These are really critical habitats in the deep ocean.
"They are the cities of the deep sea. These places are really important. And as we see the oceans becoming warmer, more acidic and in some places losing oxygen that is vital to life, these places are at the forefront of these changes."
Professor Roberts said it is vital that these habitats are protected.
Watch an interview with Professor Roberts in the video player above.