Grate

Grates are foreground blocks which allow liquids to fall through while remaining solid for everything else, acting like a drainage system.

Grates can be toggled open and closed when triggered via wire. An open grate is transparent, allowing light and liquid through, while a closed grate is opaque and acts as a solid block. If a grate is triggered while liquid is passing through it, the grate holds the liquid until it is opened again or a player uses a bucket or sponge to remove it.

Bubbles function as the opposite of grates, acting as background objects which prevent the flow of liquids through them but allow through other things like players.

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.
 * It is also a play on "grate" and "great" being pronounced the same.