a fictional creature on the planet Arrakis in the Dune universe.

Sandworms are aggressive, wormlike, dessert dwelling creatures that were sometimes ridden by Fremen on the planet Arrakis (Dune). Sandworms were the universes only known source of spice melange, a highly valued and intregal commodity until late in Frank Herberts many volumed Dune series, when the drug was replicated by the Bene Tleilax.