NASA's Perseverance Mars rover spots a scattering of bizarre bright white pebbles of a mysterious composition and origin.

In late October, the rover photographed a scattering of bright white rocks. The Martian pebbles present two big mysteries: What are they made of, and how did they get there? Bright white pebbles ...

40.5 x 30.5 cm. (15.9 x 12 in.) ...