Scientists working with NASA¡¯s Perseverance rover state emphatically that they are not claiming to have discovered life on Mars.

But many would regard a rock that the rover just finished studying as ¡°Most Likely to Contain Fossilized Microbial Martians.¡± The rover has drilled and stashed a piece of the rock, which scientists hope can be brought back to Earth in the coming years for closer analysis and more definitive answers.

¡°What we are saying is that we have a potential biosignature on Mars,¡± said Kathryn Stack Morgan, the mission¡¯s deputy project scientist. She describes a biosignature as a structure, composition or texture in a rock that could have a biological origin.