Answer:
Parabolic sand dunes
U-shaped mounds of sand with convex noses trailed by elongated arms are parabolic dunes. These dunes are formed from blowout dunes where the erosion of vegetated sand leads to a U-shaped depression. ... Sometimes these dunes are called U-shaped, blowout, or hairpin dunes, and they are well known in coastal deserts.
Explanation:
Barchans
Barchans are a crescent-shaped shifting sand dune. Barchans face the wind predominantly from one direction. They are found in sandy deserts.