This is a curious case in that it is difficult to determine exactly what NASA’s Mars Reconnaissance Orbiter HiRISE camera imaged.
There is speculation that it is an entrance to an underground base or a craft of some kind. Who knows?
Case #5: Dome and cube found on Mars:
The sunlight is seen reflecting off the side of the metallic looking dome and cube. This might even be a base. The round part is approximately 65 metres across and the walls are 7 to 10 metres thick. The object appears to be artificial as it has geometry and symmetry.
The only way to see the object clearly is by using the NASA image viewer located to the left of the web page. Click the “Toggle full page” icon followed by the “Zoom in” icon. Click on “Zoom in” until the maximum image size is displayed. The object is located in the middle right of the image.
I followed the process described above, combining several screenshots into a large, complete image which you can download here (file size: 2.78 Mbytes).
I tried downloading the original PNG, GIF, JPEG, TIFF and PDF files; however the resolution of each is too low to see the object clearly. Perhaps try downloading the JP2 file?
Original NASA source: http://viewer.mars.asu.edu/planetview/inst/hirise/PSP_009760_2650_RED
Curious image indeed, Jim!