Signs of Fluids and Ice in an Unnamed Crater in Acidalia Planitia (CTX Frame - Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)

This image shows an Unnamed Crater approx. 11 Km (about 7 miles) in diameter, located in Acidalia Planitia, part of the Northern Plains. Several features in and around this Crater are suggestive of fluids and ice at and near the surface.
The muted topography of the Crater and its surroundings, the relatively shallow floor (300 mt or 330 yards), the convex slope of its Walls — all are consistent with ice being present under the Surface, mixed with rocks and soil. Ice would have acted as a lubricant, facilitating the flow of rocks and soils and hence smoothing landscape's features such as ridges and Craters' Rims.

The concentric and radial fissures in the Crater's Floor may indicate decrease of volume due to loss of underground ice. Piles of rocks aligned along these fissures and arranged forming polygons are similar to features observed in terrestrial periglacial regions such as Antarctica.
Antarctica's features are produced by repeated expansion and contraction of subsurface soil and ice, due to seasonal temperature oscillations.

The funnel-shaped depressions visible in the Crater's Floor could be Collapse Pits, further evidence of ice decay; alternatively, they could be smoothed-out small Impact Craters.