When underground with its spines exposed, the sandwyrm can snap its spines closed on one Large, two Medium, or four Small or Tiny creatures above it. Each creature must make a successful DC 15 Dexterity saving throw or be restrained. A restrained creature can use its action to make a DC 15 Strength check to free itself or another restrained creature, ending the effect on a success. Creatures restrained by this trait move with the sandwyrm. The sandwyrm's stinger attack has advantage against creatures restrained by this trait.