Coral can be found in the ocean at both ends of the world. It can be broken and picked up by either hitting it with a Pickaxe, placing a block on its tile, or by mining out the Sand Block underneath it.
Coral can be placed as a decoration, just like Books and Crystal Shards. Once set, the piece will take on one of six appearances, which can sometimes be more than one block in width and height.
Coral spawns when a world is created and respawns very slowly afterward. If the player wants more Coral than a world's oceans can provide, they can go to another world to take about 15 freshly generated Coral per ocean.