Wet Sponge

The wet sponge is a variant of the sponge block that lacks its water-removing property. When placed, it emits water droplets from its sides and bottom, similar to the way any other block emits the droplets from the bottom when water is directly above it.

Obtaining
Ocean monuments have a chance of spawning with a room containing wet sponges. The Elder Guardian drops a wet sponge when killed by the player.

As a smelting ingredient
When smelted, an empty bucket in the 'fuel' slot will fill and become a water bucket.