While climbing on a wall or ceiling made of worked stone, the stone creeper injects its acid into the mortar, weakening the structure. Each creature within 10 feet of the wall or in a 10-foot cube beneath the ceiling must make a DC 12 Dexterity saving throw, taking 7 (2d6) bludgeoning damage on a failed save, or half as much damage on a successful one. A creature that fails its saving throw when beneath a ceiling is also knocked prone and buried. The buried target is restrained and unable to breathe or stand up. A creature, including the target, can take its action to remove the rubble and free the buried target by succeeding on a DC 10 Strength check.