In just a year and a half of its stay on Mars, the Perseverance rover found many samples of rocks, as well as an intriguing organic substance in the rocks of the planet, reports CNET.

In particular, Mars Perseverance collected two samples of a mudstone rock called Wildcat Ridge, which is located in the river delta area of Jezero crater. This rock is interesting because the organic molecules (called aromatics) found in it are considered a potential biosignature, which NASA describes as a substance or structure that can be evidence of past life, but could also have been produced without it.

The rover team emphasized that the substance is not the final proof of the presence of ancient life on the planet. Organic molecules have already been spotted on Mars by the Curiosity rover in Gale Crater, as well as by by the Perseverance apparatus, which found carbon-containing molecules at the beginning of its mission.

The rock was studied by the SHERLOC rover instrument (which stands for Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals – Scanning).

“In its analysis of Wildcat Ridge, the Sherloc instrument recorded the mission’s most abundant organic discovery to date,” NASA said.

At the same time, scientists see familiar signs in the analysis of the rock.

“In the distant past, the sand, mud, and salts that now make up the Wildcat Ridge sample were deposited under conditions where life could have thrived,” Ken Farley, the scientist of Project Perseverance said. “The fact the organic matter was found in such a sedimentary rock – known for preserving fossils of ancient life here on Earth – is important.”

Perseverance is unable to find definitive evidence of ancient microbial life on Mars. The burden of proof for establishing life on another planet is very high, according to Farley. This is why you need to study the rocks of Mars up close and in terrestrial laboratories. There are currently 12 rock samples on board the rover, including pieces of the aforementioned Wildcat Ridge and samples of another sedimentary delta rock called Skinner Ridge. Earlier during the mission, the rover also collected samples of erupted rocks that indicate the impact of ancient volcanic activity in the crater.

NASA is so pleased with the variety of samples collected that it plans to drop some of the filled tubes on the surface of the planet soon in preparation for the upcoming Mars Sample Return (MSR) campaign. The MSR is an ambitious plan to send a lander to Mars to collect samples of Perseverance and deliver them to Earth for careful study. The mission is under development and if all goes according to plan, these stones could be delivered by 2033.