Microbes are thriving deep inside the oceanic crust, away from light and devoid of any oxygen, a new study reported.

"They're gaining energy from chemical reactions from water with rock," said Mark Lever, a microbiologist at Aarhus University in Denmark and lead author of the study, reports Livescience.

For the study, Lever and his colleagues drilled the ocean floor to collect study samples. The thickness of the sediments that the researchers drilled through was close to 260 meters, according to a report from Physorg.com.  The samples were collected from a basalt rock that is believed to be some 3.5 million years old and present about 350 to 580 meters deep. The region from where the sample was collected is called as the "dark biosphere".

The researchers first ensured that they had got the native microbes from the oceanic floor and that they were not contaminants belonging to the drilling equipments. Then, the researchers incubated the microbes along water found at the drilling site (the water had high levels of chemicals and low levels of oxygen). The microbes were left to grow in the lab for more than two years, reports physorg.

After two years, researchers placed a sterilized rock in the container where the microbes were growing. The microbes were then incubated for about five more years. Study results showed that the microbes were surviving by using a process known as chemosynthesis.

Possibility of life on other planets                              

NASA had recently reported that life could have once been possible on Mars, as the Curiosity rover's analysis of rock sample showed the presence of carbon, nitrogen, sulfur and phosphorous -  elements that are required for life.

"I think it's quite likely there is similar life on other planets. On Mars, even though we don't have oxygen, we have rocks there that are iron-rich. It's feasible that similar reactions could be occurring on other planets and perhaps in the deep subsurface of these planets," Lever said, reports Livescience.

The study is published in the journal Science.