If Mars were a fruit in the produce aisle (and, lets be honest, it would make a decent-looking nectarine), NASA could slap an organic sticker on it. Kind of.

Researchers at the space agency announced Thursday that the Curiosity rover has discovered strong concentrations of organic molecules in 3-billion-year-old sedimentary rocks on the red planets surface. Those molecules are familiar building blocks for life here on Earth, including carbon, hydrogen, oxygen and nitrogen.

That doesnt mean theyve found life, but its a good indication Mars could have sustained life in the past. While Curiosity encountered organic carbon on the planets surface back in 2012 and again in 2013 , NASA said Thursday this most recent find was in concentrations 100 times greater than earlier detections.

Curiosity has not determined the source of the organic molecules, cautioned Jen Eigenbrode of NASAs Goddard Space Flight Center in a NASA release . Eigenbrode is the lead author on a paper presenting the discovery in the June 8 edition of the journal Science.