This image from HiRISE, on the Mars Reconnaissance Orbiter, shows two flat top mesas in southern Mars when the season was changing from Spring to Summer. Images Credit: HiRISE, MRO, LPL (U. Arizona), NASA
The dunes have a morphology indicating formative winds blowing from east to west (from right to left).
Barchans can move intact a downwind and can even appear to pass through each other.
Image from the Wikimedia Commons