The accidental discovery of strange life forms on a boulder beneath the ice shelves of the Antarctic has confounded scientists.

Researchers were drilling through 900 meters of ice in the Filchner-Ronne Ice Shelf, situated on the southeastern Weddell Sea, when they stumbled upon unexpected creatures "firmly attached to a rock," living in the darkness and subzero temperatures.

A collection of stationary animals — sponges and potentially several previously unknown species — were among the discoveries, CNN reports.

Animals like these aren't expected to live in these extreme locations, because they are so far from sunlight and any obvious source of food.

It was "a genuine surprise to see these animals there," said marine biologist Huw Griffiths, lead author of a new study documenting the discovery. "It's about 160 kilometers further under the ice shelf than we had ever seen a sponge before."

The accidental discovery was made by a team of geologists, who were drilling through the ice to collect mud samples but came across the rock harboring these strange creatures.