There are many types of dunes, with names like:

* Barchan dunes: Crescent-shaped dunes

* Star dunes: Dunes with multiple arms radiating outwards

* Longitudinal dunes: Long, narrow dunes aligned with the wind

* Transverse dunes: Ridges of sand perpendicular to the wind direction

While "sand mountain" isn't a formal geological term, it's a pretty accurate description of what a dune looks like!