Filter-feeding organisms, however, were not expected to be found this deep because they rely on food from above.
The scientists were, therefore, extremely surprised to find the boulder covered with the organisms.
The discovery also marks the first time geologists have stumbled upon a hard substrate – the boulder – deep under an ice shelf.
The researchers originally expected to hit upon a bed of mud at the sea floor.
Dr James Smith, a British Antarctic Survey geologist who was part of the drilling team, said: “We were expecting to retrieve a sediment core from under the ice shelf, so it came as a bit of a surprise when we hit the boulder and saw from the video footage that there were animals living on it.”
Dr Griffiths also said: “To answer our questions we will have to find a way of getting up close with these animals and their environment—and that’s under 900 meters of ice, 260km away from the ships where our labs are.