Grate

The Grate is a foreground item added in the Journey's End update. This item allows liquid to fall through, acting like a drainage system.

Bubbles function as the opposite of grates, background objects which prevent the flow of liquids through them.

Trivia

 * The tooltip for the item, which is "They'rrrre Great!", is a reference to mascot Tony the Tiger, who says this line in ads for Frosted Flakes.