Perseverance rover's Mars samples must be brought back to Earth, scientists stress 

 Sedimentary deposits sampled by the Perseverance rover could contain evidence of past Martian life. 

https://cdn.mos.cms.futurecdn.net/qpLQBBxfZ9Yks54urpKHhC.jpg

https://www.space.com/perseverance-mars-rover-sample-return