Bubble

Type	FurnitureBlock
Placeable	✔️ (1 wide × 1 high)
Use time	15 (Very fast)
Rarity
Buy	2 SC
Sell	40 CC
Research	100 required

Desktop/Console/Mobile-Only Content: This information applies only to the Desktop, Console, and Mobile versions of Terraria.

Bubbles holding all liquids. Same as other solid blocks, the topmost row of Bubbles is unnecessary when keeping liquids in place.

Bubbles are animated background furniture blocks, which have special behavior regarding liquids, interacting as if the Bubble was a solid block. When Bubbles are placed together in groups, they connect to make a larger Bubble or more complex structures.

Bubbles are purchased from the Party Girl for 2 SC each during Hardmode.

Grates function as the opposite of Bubbles, acting as solid blocks but allowing liquids to flow through.

Behavior

Placed Bubbles only allow other Bubbles to be placed adjacent to it if there is no other supporting tiles (e.g. a background wall). Bubbles cannot be hammered, and are thus unable to produce liquidfalls. Actuators do not affect Bubbles.

Liquids will collide with Bubbles as if they were solid blocks. Structures made of Bubbles can be used to contain liquids just like blocks.

If the player uses Bubbles to create a lava pool, burnable items like coins will be destroyed when contacting the lava, no matter how thin the lava is. This is because items do not collide with Bubbles, but pass through them instead, and their sprites' midpoint will be submerged in lava regardless of size.
Similar to placing other blocks over water makes them contain water, Bubbles can contain all kinds of liquids. Doing so will not change the placed Bubbles' sprite, but they have some unique interactions:
- Pressing ⚒ Use / Attack on an empty Bubble with a filled Bucket will place the Bucket's contents into the Bubble. The liquid can be removed again with an Empty Bucket. Removing the filled Bubble (e.g., with a pickaxe) will free the liquid, causing it to fall (or react with other liquids).
- Each tile of Bubble holds its liquid separately; even if the Bubbles appear to be joined, the liquid will not flow among them, nor interact with liquid in other Bubble tiles. A 2×2 Bubble square may look like a single larger Bubble, but it can hold water, lava, honey, and shimmer in separate tiles without letting them react.
- Bubbles with a liquid inside of them will act just as if they were their respective liquid. For example, it is possible to swim and drown in a water-filled Bubble; players can walk on liquid-filled Bubbles using water-walking effects from Water Walking Boots (or its upgrades) or a Water Walking Potion.
- Liquid in Bubbles can react with a slower kind of (flowing) liquid above or next to it. This will always consume the entire contents of the Bubble tile, and however much was in the other tile.
Note that when reloading the world, liquids contained in Bubbles will be released if there are no blocks supporting them, or removed if they are supported, just like liquids contained in other solid blocks.
Liquid that is supported/confined by Bubbles (but not contained in Bubble tiles as described above) will remain in place.

Notes

Although Bubbles are not solid blocks, they are still considered valid frame tiles for housing. They are invalid home tiles, however.
- (Old-gen console and 3DS versions) NPCs will occasionally move out of houses that use Bubbles as frame, making these kind of houses unreliable for accommodating NPCs.
Although Town NPCs will walk through empty Bubbles and Bubbles filled with water or honey, they will not walk through lava-filled Bubbles. Critters and enemies will walk through lava-filled Bubbles, though.
Bubbles have a rarity of 00*, so they can be destroyed by lava.
Bubbles are essentially the opposite of a Grate, one letting in entities but not liquids and the other letting in liquids but not entities. One notable difference is that unlike Grates, Bubbles cannot be toggled on or off, not even with Actuators.

Tips

Once placed, surrounding blocks and background walls can be removed, leaving a free-standing Bubble.
A liquid-filled Bubble and a Liquid Sensor can be used for a "reload detector", allowing complex circuits or machines to be restarted on world load. However, the Bubble will need to be manually reloaded before the next restart.
Honey-filled Bubbles are perfect for Honey buff pickups for arenas.
Using Bubbles for the frames of a house grants easy access to it. This can be useful for the Nurse's house when going for healing in a hurry.
Care should be taken with setting lava traps for flying enemies, as the lava will kill flying critters as well.
Since water will trigger the Cute Fishron mount's boosts, the player can make several Bubbles of water around their world, so they would be able to travel at high speed using the mount.
In adventure-themed Terraria maps, Bubbles can be used as a filter to any liquid, including lava. This can be used to create scenarios like "lava stream escaping".