This image from NASA's Mars Reconnaissance Orbiter shows a hill with a central crater. Such features have been interpreted as both mud volcanoes (really a sedimentary structure) and as actual volcanoes (the erupting lava kind).
NASA's Mars Reconnaissance Orbiter (MRO) keeps finding new impact sites on Mars. This one occurred within the dense secondary crater field of Corinto Crater. The new crater and its ejecta have distinctive color patterns.
This image from NASA's Mars Reconnaissance Orbiter (MRO) shows the permanent polar cap of Mars, encircled by sand dunes and looking like pulled threads. These dunes march across a fabric of patterned ground.
NASA's Mars Reconnaissance Orbiter shows bright ripples line the topography in this region, formed within a past climate. Dark dunes and sand streaks, composed of basaltic sand, have moved and filled lower areas, pushed by more recent winds.