Sponge

Sponge is a block which absorbs water, becoming a wet sponge.

Obtaining
A sponge can be obtained by drying a wet sponge in a furnace. Wet sponges are dropped when Elder Guardians are defeated, and may be harvested from sponge rooms in ocean monuments.

Drying
A wet sponge can be dried in a furnace, making the sponge reusable. If a bucket is in the fuel slot at the time the sponge completes its drying, either because the player places it there or because the fuel slot had contained a bucket of lava, the water will drain into the bucket, leaving a bucket of water in the fuel slot.

Usage
Sponges absorb water source blocks around themselves, out to a taxicab distance of 5 in all directions. The sponge must be directly touching a water source to absorb water, and will only absorb water connected to an adjacent water block touching the sponge.

When a sponge absorbs water, it will convert to a wet sponge, which is darker, drips water, and is unable to soak up any more water.