Crescentic

A crescentic dune with a star dune superimposed on its crest is the most common complex dune.

Some types of crescentic dunes move more quickly over desert surfaces than any other type of dune.

The broken pumice is clear and isotropic, and very small particles commonly have crescentic, sickle-shaped, or biconcave outlines, showing that they are produced by the shattering of a vesicular glass, sometimes described as ash-structure.