Artifact whose main purpose is to soak up water and apply it to other things. It removes a pool or moat square or dries up a fountain when applied to one (moats may refill), gaining a charge each time. You can apply it to spend a charge blanking a scroll, erasing an engraving (any type, not just dust), cleaning your face or hands, and extinguish fiery monsters such as a flaming sphere (possibly instakilling them).

The initial idea was to create a “sponge” object as the base item type, but since it’s undesirable to make a new object just to be the base of an artifact, it could instead either be a “spongestone” gem, or just an artifact towel, since towels can already soak up water. (If implemented as a towel, the towel would only gain one charge of wetness when immersed in water, and could attempt to dry up that square immediately.)