Dragon Egg

The Dragon Egg is a block that spawns on top of the Bedrock portal created by the defeat of the Enderdragon in The End. Left or right-clicking it seems to cause it to teleport to a place nearby, when falling through the air after teleporting it will create particles similar to that of and enderman or a portal. Hitting one with a pickaxe will destroy it.

History
The Dragon Egg is an item first mentioned by Notch on the 27th of October, 2011 on which Notch was supposedly working before the feature freeze, though it seems to have been worked on during it.

The Ender Dragon Egg was first introduced in Beta 1.9 Pre-release 6 (November 11th 2011).

As of Beta Pre-release 6, the Dragon Egg has no crafting use. When torches are placed right under the dragon egg it crashes the game. (Fixed as of Minecraft 1.0.0)

Also when the Ender Dragon Egg is hit with either mouse button, the Egg teleports.

As of so far the only way to obtain an Ender Egg is to either use inventory hacking or push the Egg with a piston, or placing a torch under it as it falls. A new way found by Zooka128 is to start trying to break the Ender Stone and then whilst hitting it with your fist drag the crosshair over the egg and it will then turn into an item that you can pick up.

Dragon eggs are affected by gravity and drop to the ground when placed in the air.

Trivia

 * It may teleport up to five blocks in either direction along the y axis and fifteen block along the x and z axis. This gives it a 31x31x11 volume of space where it may teleport within.
 * The egg may teleport into open air, which will cause it to fall to the ground in the same fashion as sand or gravel. This does not damage it.
 * Redstone currents cannot pass through one.
 * Attempting to push it with a piston causes it to drop as a resource.
 * Destroying its accompanying Overworld Portal with water or lava will also cause it to drop as a resource.
 * Enderdragons destroy Dragon Eggs when passing through them.
 * It turns into a resource in a similar way as sand or gravel, when falling on a partial block such as a torch. This works with all non-solid blocks.
 * The writer of the Minecraft comic WonderCraft, Samcube, was requested by Mojang to create official Minecraft posters for possible purchase. In part of these works, one can see an area with an Enderdragon and a chicken on top of a Huge Mushroom. In the same scene is a purple, egg-shaped block like entity near the chicken - this was the Dragon Egg.
 * You can gather the egg by looking away while holding in the left click and then looking at it still holding the left click. If done right it won't teleport away on contact(as of 1.9 Pre 6)