Still no subsurface Martian cows. But otherwise, the story of methane on the red planet gets more interesting.https://www.nytimes.com/2019/04/01/science/mars-methane-gas.html …
It's possible. If life ever rose early in Mars history, it could have migrated underground when the surface turned inhospitable. There's tons of life in the rocks of Earth.https://www.nytimes.com/2016/09/13/science/south-african-mine-life-on-mars.html …