If Mars were a fruit in the produce aisle (and, let’s 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 planet’s surface. Those molecules are familiar building blocks for life here on Earth, including carbon, hydrogen, oxygen and nitrogen.

That doesn’t mean they’ve found life, but it’s a good indication Mars could have sustained life in the past. While Curiosity encountered organic carbon on the planet’s 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 NASA’s 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.

NASA's Curiosity rover is seen on lower Mount Sharp in this low-angle self-portrait taken Aug. 15, 2015. (Photo: NASA/Jet Propulsion Laboratory-Caltech/Malin Space Science Systems via Reuters)

“Whether it holds a record of ancient life, was food for life, or has existed in the absence of life,” Eigenbrode continued, “organic matter in Martian materials holds chemical clues to planetary conditions and processes.”

The organic-rich sample came from the bottom of what used to be a massive lake inside Gale Crater billions of years ago. That’s particularly exciting since water ― so far as we know ― is also an essential ingredient for life.

And in a separate report in Science set to publish Friday, scientists revealed the Curiosity rover has also detected methane on the Martian surface in concentrations that vary with the seasons. The methane concentrations peak near the end of the northern hemisphere’s summer, then dwindle in the winter.

The methane could simply be the product of basic geological processes, but it’s possible the gas has origins in biological sources.

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Curiosity at Work on Mars

This artist's concept depicts the rover Curiosity, of NASA's Mars Science Laboratory mission, as it uses its Chemistry and Camera (ChemCam) instrument to investigate the composition of a rock surface. ChemCam fires laser pulses at a target and views the resulting spark with a telescope and spectrometers to identify chemical elements. The laser is actually in an invisible infrared wavelength, but is shown here as visible red light for purposes of illustration.

Daybreak At Gale Crater

This computer-generated view depicts part of Mars at the boundary between darkness and daylight, with an area including Gale Crater beginning to catch morning light.

Curiosity Launch Vehicle

The Atlas V 541 vehicle was selected for the Mars Science Laboratory mission because it has the right liftoff capability for the heavy weight requirements of the rover and its spacecraft.

Mars Science Laboratory Spacecraft During Cruise

This is an artist's concept of NASA's Mars Science Laboratory spacecraft during its cruise phase between launch and final approach to Mars. The spacecraft includes a disc-shaped cruise stage (on the left) attached to the aeroshell. The spacecraft's rover (Curiosity) and descent stage are tucked inside the aeroshell.

Curiosity Approaching Mars

The Curiosity rover is safely tucked inside the spacecraft's aeroshell. The mission's approach phase begins 45 minutes before the spacecraft enters the Martian atmosphere. It lasts until the spacecraft enters the atmosphere.

Curiosity Inside Aeroshell

The Curiosity rover and the spacecraft's descent stage are safely tucked inside the aeroshell at this point. The aeroshell includes a heat shield (on the right, facing in the direction of travel through the atmosphere) and backshell. The diameter of the aeroshell is 14.8 feet (4.5 meters), the largest ever used for a mission to Mars.

Mars Science Laboratory Guided Entry At Mars

The mission's entry, descent, and landing (EDL) phase begins when the spacecraft reaches the top of Martian atmosphere, about 81 miles (131 kilometers) above the surface of the Gale crater landing area, and ends with the rover safe and sound on the surface of Mars. During the approximately seven minutes of EDL, the spacecraft decelerates from a velocity of about 13,200 miles per hour (5,900 meters per second) at the top of the atmosphere, to stationary on the surface.

Deceleration of Mars Science Laboratory in Martian Atmosphere

This artist's concept depicts the interaction of NASA's Mars Science Laboratory spacecraft with the upper atmosphere of Mars during the entry, descent and landing of the Curiosity rover onto the Martian surface.

Mars Science Laboratory Parachute

This is an artist's concept of the Mars Science Laboratory Curiosity rover parachute system.

Curiosity While On Parachute

This is an artist's concept of NASA's Curiosity rover tucked inside the Mars Science Laboratory spacecraft's backshell while the spacecraft is descending on a parachute toward Mars. The parachute is attached to the top of the backshell. In the scene depicted here, the spacecraft's heat shield has already been jettisoned.

Curiosity And Descent Stage

This is an artist's concept of the rover and descent stage for NASA's Mars Science Laboratory spacecraft during the final minute before the rover, Curiosity, touches down on the surface of Mars.

Curiosity's Sky Crane Maneuver

The entry, descent, and landing (EDL) phase of the Mars Science Laboratory mission begins when the spacecraft reaches the Martian atmosphere, about 81 miles (131 kilometers) above the surface of the Gale crater landing area, and ends with the rover Curiosity safe and sound on the surface of Mars.

Curiosity Touching Down

This artist's concept depicts the moment that NASA's Curiosity rover touches down onto the Martian surface.

A Moment After Curiosity's Touchdown

This artist's concept depicts the moment immediately after NASA's Curiosity rover touches down onto the Martian surface.

Curiosity Mars Rover

This artist concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life.

Curiosity's Close-Up

In this picture, the mast, or rover's "head," rises to about 2.1 meters (6.9 feet) above ground level, about as tall as a basketball player. This mast supports two remote-sensing instruments: the Mast Camera, or "eyes," for stereo color viewing of surrounding terrain and material collected by the arm; and, the ChemCam instrument, which is a laser that vaporizes material from rocks up to about 9 meters (30 feet) away and determines what elements the rocks are made of.

Mars Rover Curiosity

This artist concept features NASA's Mars Science Laboratory Curiosity rover, a mobile robot for investigating Mars' past or present ability to sustain microbial life.

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This article originally appeared on HuffPost.