And though researchers were unable to extract DNA from the Martian rocks, the finding nonetheless adds intrigue to the search for life beyond Earth.
Results of the study were published in the latest edition of the journal Astrobiology.
Martin Fisk, a professor of marine geology in the College of Oceanic and Atmospheric Sciences at Oregon State University and lead author of the study, said the discovery of the tiny burrows do not confirm that there is life on Mars, nor does the lack of DNA from the meteorite discount the possibility.
"Virtually all of the tunnel marks on Earth rocks that we have examined were the result of bacterial invasion," Fisk said. "In every instance, we've been able to extract DNA from these Earth rocks, but we have not yet been able to do that with the Martian samples.
"There are two possible explanations," he added. "One is that there is an abiotic way to create those tunnels in rock on Earth, and we just haven't found it yet. The second possibility is that the tunnels on Martian rocks are indeed biological in nature, but the conditions are such on Mars that the DNA was not preserved."
More than 30 meteorites that originated on Mars have been identified. These rocks from Mars have a unique chemical signature based on the gases trapped within. These rocks were "blasted off" the planet when Mars was struck by asteroids or comets and eventually these Martian meteorites crossed Earth's orbit and plummeted to the ground.
One of these is Nakhla, which landed in Egypt in 1911, and provided the source material for Fisk's study. Scientists have dated the igneous rock fragment from Nakhla which weighs about 20 pounds at 1.3 billion years in age. They believe that the rock was exposed to water about 6
Contact: Martin Fisk
Oregon State University