On December 26, scientists drilling near an underground lake by the South Pole found the remains of a dead tardigrade, a microbial animal that lives in extreme conditions, more than 3,200 feet underground, according to a report published Friday in Nature. David Harwood, one of the micro-palaeontologists involved with the research, called the findings “fully unexpected.”

It’s extremely rare for scientists to find evidence of life in Antarctic subglacial lakes, never mind finding life buried a whole kilometer underground. The last time scientists found evidence of life in a subglacial Antarctic lake was back in 2013, when scientists found 20 cultures of bacteria in Lake Hodgson, which is 305 feet underground.

Right now, it’s unclear whether the animal lived in Antarctica ocean water that froze over on the surface, or if subglacial rivers moved the tardigrade carcass from Antarctic mountains into the nearby valley. Scientists will know more once they sequence the tardigrade DNA and determine what type of environment they would have thrived in.

But if this tardigrade did indeed live underground, the implications would be huge. In many ways, the Antarctic environment resembles the polar landscapes on planets like Mars, which have ice caps. Finding evidence of life under the ice strengthens a possibility that scientists have long postulated: that Mars may have once been home to life.

This particular research is a part of the Subglacial Antarctic Lakes Scientific Access (SALSA) program, which involves using a hot water drill to bore into an ice sheet in Western Antarctica, the most rapidly melting region of the frozen continent.

According to Nature, the researchers believe that the tardigrade lived in ancient glacial meltwater from interglacial periods, which are warm periods between Ice Ages. This means the tardigrade was most likely alive either the early Holocene (50,000 years ago) or the Eemian (120,000 years ago) period. They won’t have an answer until they use radiocarbon dating on the carcasses and sequence their DNA.

The tardigrade actually resembles species that are native to damp soil and lived among plants and fungi that were also native to land, according to Nature. Scientists won’t know if the tardigrade was terrestrial or aquatic until they sequence the creature’s DNA.

The borehole from the SALSA program that lead to the tardigrade carcass was sealed off on January 5, according to Nature, and the SALSA researchers will now be focusing on analyzing the samples that they’ve collected from the subglacial environment.