all that for a few billions

Anyone know exactly how the rover took a selfie without any apparent camera attachment to the body of the vehicle?

Girl, It has a drone.

See here : https://www.jpl.nasa.gov/video/details.php?id=1171#fragment-1

So, from Zebra's video link (thanks!), it does have a camera on an arm that took multiple pictures, which were then stitched together to form the selfie. Apparently the arm itself was removed from the composite image. Cool.

BTW, I'm not sure there's a dense-enough atmosphere on Mars for a drone to fly.

Thanks, I was wondering too!