Seastone (海楼石 Kairōseki?, translated as "Seastone"; literally meaning "Sea Watchtower Stone"), called Sea-Prism Stone in the English versions, and Cherry Stone in One Piece: Grand Battle, is a naturally occurring (though apparently rare) substance that can drain the energy of Devil Fruit users to the point where they can't consciously control their powers. Dr. Vegapunk has invented revolutionary ways to use this rare substance. The Marines appear to have vast quantities of it, using it for jail cells, handcuffs, weapons, and the bottoms of battleships.