Coral Block

Coral block is a solid block which comes in five variants: tube, brain, bubble, fire, and horn.

Dead coral block is a solid block which comes in the same variants as coral blocks.

Obtaining
Coral blocks can only be obtained with a pickaxe enchanted with Silk Touch, otherwise they will drop the respective dead coral. Dead coral blocks can be obtained with any pickaxe.

Natural generation
Coral blocks naturally generate in coral reef structures. These are found in warm oceans.

Usage
Coral blocks and their dead variants can be used as building or decoration blocks.

Dead coral blocks
In order for coral blocks to stay alive, at least 1 of the blocks surrounding it must be water. If placed outside of water, it will transform into its respective dead coral block, but can be brought back alive by being surrounded by at least 1 block of water again, which will cause it turn back into it's respective coral block again.