Unnamed "Ghost" Crater near the South Pole (CTX Frame - Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit)

This HiRISE image shows a Circular Structure near the South Pole of Mars. This feature is probably a heavily modified Impact Crater. It is currently expressed as a group of concentric circular features with little vertical expression.
This feature was probably once an Impact Crater many tens of meters deep. (Small impact craters are typically about 1/5th as deep as they are wide).
The original topography has been smoothed by some combination of burial and viscous relaxation. Most burial processes will preferentially fill in low areas like craters; the infilling material may then compact, producing arcuate structures.