(CNN) During its time on Mars, NASA's Curiosity rover has focused on understanding the planet's potential habitability in its ancient past, drilling into rocks and studying their dust to determine possible conditions for life. The rover has found some intriguing clues, and now, scientists are following up on those puzzle pieces to understand their origin.

In 2018 , the rover hit pay dirt when it found organic matter in soil samples of three billion-year-old mudstone in the Gale crater.

Curiosity sampled sites by drilling five centimeters below the surface in the Gale crater, which is where the rover landed in 2012. The 96-mile crater, named for Australian astronomer Walter F. Gale, was probably formed by meteor impact between 3.5 to 3.8 billion years ago. It likely held a lake, and now includes a mountain called Mount Sharp.

The rover was able to heat the samples to between 932 and 1,508 degrees Fahrenheit and study the organic molecules released through gas analysis. The organic molecules and volatiles, comparable to samples of sedimentary rock rich in organics on Earth, included thiophenes, methylthiophenes methanethiol and dimethylsulfide.

They don't exactly roll off the tongue, but researchers believe that these are fragments of larger molecules that were present on Mars billions of years ago. And the high amount of sulfur in the samples is most likely how they've lasted so long, the researchers said.