Egg

An Egg is an item laid by chickens every 5–10 minutes. They can only be stacked together in groups of up to 16, unlike most items. While they cannot be eaten directly, they can be crafted into a couple of food items, or used as a weak but rapid missile.

When thrown, eggs have the same particle effect on impact as snowballs and additionally have a $1⁄8$ chance of spawning one baby chicken. If that happens, there is an additional $1⁄32$ chance of the egg spawning 4 baby chickens instead of one (or, a $1⁄256$ chance). This also works in The Nether and The End.

Resource farming


Since eggs can be made into cake and pumpkin pie, and are probably the rarest item in the cake recipe to acquire through normal activities, it can be useful to try to stock up on as many as you can. An easy way to accumulate eggs is to dig a deep pit (preferably at least 3x3, 24 blocks deep). If your pit is deep enough, all non-chicken mobs will die when they stumble into it, thus protecting you from aggressive mobs. If you wait long enough, eventually chickens will fall in of their own accord and start laying eggs. It helps to periodically return to the surface to see if a chicken flock has spawned around your pit. (Animals do spawn, although very rarely, so you will need to lead chickens to your pit.) While you can push them in yourself, or knock them in with snowballs, the easiest way to lead chickens is to hold seeds in your hand, which will make them follow you. Leads can also be used, though are harder to acquire in the earlier stages in the game because of the slimeballs needed to craft them.

Another way to easily get eggs is to make a 1x1 room with a hopper as the floor, and then put a chicken in it. Any eggs that the chicken lays will fall into the hopper, where you can collect them directly from the hopper or put a chest below the hopper. This may not work with more than one chicken in each room, because the chickens might suffocate in the walls. Also, fences will not work as walls because eggs will get stuck next to the fence and will not go into the hopper. If you have more than a 1x1 space, you could make a system where half of the hoppers lead to dispensers and hatch more eggs automatically.

If the player has already collected one or more stacks of eggs they can be thrown to manually spawn baby chickens in a confined area. Each stack has an 88% chance of producing at least one chick, and will average slightly over two. This allows producing a chicken farm anywhere, but it can take quite a few eggs to get things started. If you already have chickens available, it's best to first breed them with seed to produce a large flock, which can then produce enough eggs to replace a decent "harvest" of chickens.

History
The Egg was added in the 7 Seecret Friday Update. During the Beta update (20 of December, 2010), eggs were made throwable at the request of a fan as a result of this Twitter conversation.

As of Beta 1.9 pre-releases, it is rather easy to start a farm with as few as two or even one chicken, as they can reproduce both by breeding and (albeit unreliably) with eggs.

Until Minecraft 1.0 RC1 eggs hatched adult chickens because baby animals had yet to be added.

Bugs

 * When a chicken is spawned by an egg in Pocket Edition, it will have 9 health instead of 4.
 * Thrown eggs will vanish when a world is reloaded, and custom spawners cannot create them. Both of these issues are caused because thrown eggs no longer have an Entity ID, unlike most entities.
 * In Pocket Edition, a thrown egg will spawn adult chickens only, no babies.

Trivia

 * Like arrows and snowballs, eggs are fired from the dispenser and have the same effects as a thrown snowball when placed into a dispenser and then activated. Eggs fired in this manner have the same chance of spawning chickens when breaking on the ground.
 * If an egg is thrown through lava, it will catch on fire similarly to an arrow, and will not burn away.
 * If an egg is thrown through water, it will leave a trail of bubbles, much like snowballs and arrows do.
 * Eggs push mobs back, but do not deal damage to them.
 * However, thrown eggs deal damage to the Ender Dragon, but since they deal so little damage it is only practical to kill the Ender Dragon this way in Creative mode.
 * If the player is standing near a chicken when it lays an egg, a "pop" can be heard.
 * Throwing eggs at neutral enemies will provoke them.
 * Eggs will break midfall if hit by another projectile; The chance of spawning a baby chicken is not affected.
 * Throwing an egg at a portal will break the egg when it hits the portal, but a spawned chicken will still go through the portal.
 * If a player is killed with eggs, it will say "[victim] was pummeled by [killer]". This message is unused because eggs don't cause damage. Ender pearls and snowballs will also display this message.
 * If an egg is thrown at an adult chicken and a baby is spawned, the baby chicken will follow the adult chicken around, thinking the adult chicken is its mother/father.
 * Despite chickens being birds, they give offspring immediately after being bred with seeds.
 * In order to have a 99% confidence level of getting a chicken from an egg, 35 eggs are required. As eggs only stack up to 16, if you want to be (almost) sure of getting a chicken, 32 eggs are recommended. Also, each stack offers a 62% chance of getting at least two chickens (which will allow you to breed them with seeds).