Caves in the ice carved out by the warmth of hidden volcanoes on Ross Island in Antarctica are sheltering animals and plants that seem to be unknown to science, scientists have found.

DNA sequencing of organic matter from soil in the caves has revealed traces of DNA from algae, mosses and small animals. Some of these DNA sequences didn't match any of the known species to live in Antarctica.

"That might just be because there are plants and animals in Antarctica that we haven't sequenced at those parts of the genome before, so they might just be your bog-standard plants and animals from Antarctica," said study author Ceridwen Fraser of the Australian National University in a statement.

"Or they might indicate something more exciting, like species that we don't know anything about yet," she continued.

The caves are an oasis of warmth in an otherwise harsh and unforgiving environment. Temperatures at Ross Island, a small volcanic island off the coast of Antarctica in the Ross Sea, are below 0C all year round.

Mount Erebus, the southernmost active volcano on the planet, made the caves from steam escaping via its central crater. The caves reach a balmy 25C, and are one of the few natural places in Antarctica you could comfortably stay wearing just a T-shirt. It is a unique potential haven for complex plant and animal life to live.

"It's completely conceivable that there might be species living under the ice in Antarctica that we know nothing about that have adapted to those cave geothermal environments. That would be really cool," said Fraser.

"There was one set of sequences that look like they're from some sort of arthropod, and arthropods are things like spiders, mites, a lot of insects. You could imagine maybe a cave mite or some sort of insect-like organism that's down there."

The next stages in the research are to try to witness living plants and animals occupying the cave. The traces of DNA found are promising, but there is a chance that they blew in from further afield, rather than originating in the caves. The researchers will return to Antarctica in the next two years to search for more signs of life.

"To be honest I don't think people have really looked yet, so it's quite possible that there is life under the ice that we haven't seen."