Coral Reefs are decorative blocks that are found underwater. They come in a variety of colours, such as blue, green, purple, yellow and red. Being living animals that require the photosynthetic activity of small plants in their tissues (zooxanthellae) to gain nourishment and survive, they can only survive when exposed to light, and thus are usually found in the shallower reaches of the ocean.
Coral Reefs are interesting blocks, in that, while they only take up one block's space, they also include a non-solid image above them. The coral reef block itself is greenish-blue in colour, but the corals on top are of varying colour. Similarly to Waste Blocks, the texture of the coral on top of the block is dependent on the coordinate of the block.
Coral Reef blocks can be found in the Sea biome, under the water. If a block is mined with a pickaxe, it will drop one to two pieces of Coral, but if it is mined with a pickaxe with the Silken Modifier, it will drop itself.
Coral Reef blocks are mainly used for decoration, because of their vibrant colours. However, they can also be used (to a small extent) for defense. When an entity walks on top of a Reef block, it is occasionally dealt 1 () point of damage.