Dragon eggs are available in the 9 colors corresponding to the dragon they hatch. You can only get them from temples.
Dragon eggs take up one block of space. They are the color of the temple they were found in, and hatch a dragon of the same color.
Right click an egg to hatch the dragon. But they might poop when hatching.
In Survival mode, mine the egg to pick it up. [Mod] But there is a chance that the egg will disappear forever.