In those drill sites, Curiosity detected deposits containing an iron carbonate material called siderite. According to Ben Tutolo, a University of Calgary associate professor of Earth, Energy, and Environment Studies as well as a NASA Mars Science Laboratory Curiosity Rover team, the data marks a major moment in the search for extraterrestrial life.

NASA believes that examining other sulfate-rich areas could validate these findings and further illuminate Mars’ transformation as its atmosphere dissipated.

NASA’s Curiosity rover has discovered siderite, a carbonate mineral, beneath Mars’ surface—providing new clues that the Red Planet may have once had conditions suitable for life billions of years ago.