Handy, I think you may have solved the mystery.
If that ring with the phillips head screws embedded, ever pressed into a soft surface, you’d expect to find the sort of impression we see in the NASA image.
Good job!
Thank you. Of course we still don’t know the scale of the rover image. But that “tamper-proof” style phillips screw head sure bears a resemblance. You can just imagine the spectrometer moving into position and also making the mark to the left of the screw imprint. And yes, it is the screw head at 9 o’clock that shows that same profile.