Minecraft wiki entry for End_Crystal, associated text: An ender dragon being hit with the "healing beam" of an end crystal.
An end crystal.
An example of the end crystal water trick explained in the trivia section.
An end crystal in the Overworld spawned using /summon end_crystal.
End crystals respawning the ender dragon.
A caged end crystal.
A player trying to respawn the ender dragon.
An animation of the item of the end crystal.