Limestone is a solid natural cubic block of tier 2 hardness. It has a whitish slightly grey topside and underside with a few dark grey stripes, very similar to an Ashenwood block.
However, the 4 sides of Limestone are darker with thick and thin stripes of different shades of grey, somehow similar to Bedrock, just brighter in color and not brown-beige, but whitish grey.
Limestone blocks can be placed just like they are for building purposes, or on/in any display containers, they can be processed into rods and slabs and they are used for crafting - mainly for building blocks.
On natural blocks of Limestone, Night Rocksters, Night Pigsies and Mirus are able to spawn in unlit areas during day and night. Stone Treasure Chests are also able to spawn on Limestone blocks in dark spots anytime.
Where to find
Limestone blocks can be found on the Fossil layer just below the surface of all biomes, either accessible through shallow Caves or if you simply dig downwards. The Fossil layer is made of Stone, Bedrock and Limestone with Fossils and Magnetite strewn in.
Ocean floors are mainly made of Limestone under a rather thin layer of Sand. If you need a large quantity of Limestone, it's worth to dig into ocean beds for this.
The Fossil layer can be accessed at an higher altitude through caves in Mountain biomes. Sometimes recesses at (often frozen) rivers in Mountains are "buried" into Fossil layer rocks and such make them accessible on the surface. Occasionally you can even see Fossil layer rocks like Limestone laid bare high up at steep cliffs of Mountains or Canyons.
In Creativerse, all Limestone blocks are already part of the template worlds that each newly created Creativerse game world is a copy of. Since Limestone blocks cannot grow nor spawn, no further Limestone blocks are generated in any game world after world creation.
How to obtain
You will need to equip a Stone Mining Cell (or an even stronger Power Cell) to pull / mine rocks of tier 2 hardness like Limestone, Bedrock, Limestone, Magnetite, Canyonstone (including Ruddy Canyonstone and Dark Canyonstone), Tourmaline, Mold, Peakstone or Ice.
Another alternative to mine Limestone instead of pulling it block by block would be to place Excavators (not to be confused with Extractors) on it. Even the basic (and weakest) Excavator can remove all Fossil layer blocks like Stone, Bedrock, Limestone, Fossils and Magnetite in the size of 7x7x7 blocks maximum. Half of the removed blocks will be saved in Loot Bags.
You can also dig through Limestone by destroying it. Common TNT can destroy blocks from the Fossil layer like Limestone and Bedrock and other tier 2 rocks. Please note that TNT is a destructive Explosive that will produce a crater and will not leave any blocks behind that could be collected.
Excavators and TNT-type Explosives will remove or destroy nearly all types of crafted blocks and objects like torches, furniture, signs, windows, all crafted building blocks, stairs etc., even up to Corrupted Stone Walls. However, these area-damaging Explosives will leave all Ore Nodes intact, also all storage containers, crafting stations and any objects that can contain blocks/items, including Extractors.
You can prevent all area-damaging Explosives from being used on your game world or player claim by disabling the option "TNT enabled" on claims and/or enabling the world option "Disable Explosives".
How to use
Blocks of natural Limestone can placed as they are and can be made into artificial Biomes this way where Night Pigsies, Night Rocksters and Mirus will spawn in complete darkness, but also Stone Treasure Chests now and then.
If you want to use natural unprocessed Limestone as a building block, you might want to carefully illuminate all Limestone blocks with crafted luminaires to prevent aggressive or simply unwanted Creatures from spawning.
Limestone is a valued raw material for crafting, mainly for a range of different building blocks.
Like Stone and Bedrock, one block of Limestone can be cut into either 4 Stone Slabs or 8 Stone Rods in a Processor. No crafting recipes are needed for that, you simply have to carry Limestone blocks in your bag or quickbar when activating a Processor that has been placed into the game world by pointing your cursor at it and either clicking your right mouse button or typing "f" (as the default key).
8 (blocks of) Limestone are required to craft common TNT in your Crafting Menu.
Limestone can also be crafted into a variety of nearly clear white-colored cubic building blocks, like Limestone Walls, Carved Limestone Walls, Limestone Pedestals, Straight Limestone, Spiral Limestone, and the Store exclusive cubic building blocks Chiseled Limestone Columns (this one is a cubic block despite its name), as well as the Store-exclusive blocks Chiseled Limestone Laurel Accents, Chiseled Limestone Spiral Accents, Figured Limestone Walls, Ornamental Stone Walls and Ornamental Swirl Stone Walls. All of these blocks can be crafted in your Crafting Menu.
You can then process 2 cylindric Straight Limestone Columns from one block of Straight Limestone Wall, and 2 cylindric Spiral Limestone Columns from one block of Spiral Limestone Wall in a Processor without needing any crafting recipes to be unlocked.
Other than that, Limestone is required to craft Limestone Roofs and Limestone Stairs in your Crafting Menu. Inner and outer corner blocks for Limestone Roofs, and inner and outer corner blocks for Limestone Stairs can be cut in a Processor without the need for any crafting recipes.
Please note that Limestone Slabs, Limestone Slopes and Limestone Columns can only be produced in a Processor from white Limestone Walls that have to be crafted first. These Slabs, Columns, Slopes and their corner blocks cannot directly be processed from natural rough Limestone blocks.
Limestone cannot be corrupted nor transformed in any other way in the game world.
No Quests requires Limestone to be completed, and Limestone is also not part of any quest reward.