Examples of shells chewed by Rattus rattus in predating Otala lactea. Hundreds of Otala were estivating on a building, the rats either removed them from their estivation location or opportunistically predated them as they left the building following an increase in moisture associated with a modest winter rain event.
Camera trap images that confirm black rats as the predator:
https://www.inaturalist.org/observations/68169475
https://www.inaturalist.org/observations/68169197
https://www.inaturalist.org/observations/68169198