Spawn Egg

A Spawn Egg is an item that may be used to spawn mobs directly. It is available to regular players in Creative Mode and to server ops in both Creative and Survival Mode. It allows the player to spawn a variety of mobs on command, although some mobs are not available in Item Selection for certain reasons.

Use
A Spawn Egg is used by right-clicking on a surface with the egg. The egg's mob will appear with its feet immediately adjacent to the surface.

Unlike Chicken Eggs and Ender Pearls, Spawn Eggs are not thrown; the player must be within normal range of the block.

Hostile mobs spawned while on the Peaceful difficulty setting will instantly vanish, just like mobs from Monster Spawners.

Spawn Eggs on Survival Multiplay (SMP) Servers
Spawn Eggs can be obtained by ops using the SMP Command. When using this method, the damage value of the egg spawned pertains to the Entity ID of the entity it makes. Not only does this allow the player to spawn unavailable mobs such as Giants, it allows them to spawn Minecarts and even Primed TNT.

The format for the  command is:
 * Example:  would give a player a single Villager Spawn Egg.
 * Example:  would give a player a single Villager Spawn Egg.

(You can also set 'damage' value to 120, 63, 95, 53, ect. to create a spawn egg in INVedit.)

Trivia

 * Prior to 12w01a, There was only one texture for the Spawn Mob eggs. The game hue shifted this texture to create different colors. The unaltered sprite was used by Spawn Mooshroom.
 * In 12w01a, the egg and its markings had their textures separated in order to allow them to have entirely different colors. This allowed their colors to be changed to better suit the mobs themselves.
 * Since they are not used as projectiles, attempting to fire them from a Dispenser will result as them simply being dropped as an item.
 * Mobs spawned via this item act the same as normally spawned ones. As such, hostile mobs will despawn if the player ventures too far.
 * Eggs spawned using the /give command which spawn entities other than the ones already provided will always be white with slightly darker spots, which are the modified sprites.
 * By default, Spawn Eggs can only be used once in Survival Mode. In Creative Mode, the player has unlimited uses.
 * As of 12w03a, spawn eggs will spawn mobs from dispensers instead of throwing them.

History
Spawn Eggs were added in the weekly Pre-release 11w49a and later included in the 1.1 Official Release.