Coral

Coral is a transparent block that can only be placed underwater. It comes in five variants: tube, brain, bubble, fire, and horn.

Obtaining
Coral can be instantly mined and will always drop themselves.

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

Usage
Coral can be used as a building or decoration block.

Trivia

 * In real life corals are colonies of sessile (immobile) animals.