Eye of Ender

An Eye of Ender is a crafted item the player can use to repair an Ender Portal Frame block or locate a nearby Stronghold (the only location Ender Portals can be found in) by right-clicking.

When the Eye is thrown, it will float diagonally upwards for about 15 blocks in the direction of a stronghold, emitting a trail of purple particles. The Eye will float in the air for 3 seconds before either falling back to the ground as a collectable item or shattering (explosion of particles) and returning to the End (disappearing). When the player throws the Eye when within about 20 blocks of stronghold, the Eye will float towards the ground.

Players traveling to the End are advised to craft multiple Eyes of Ender since each one has a chance of disappearing after being used to locate the Stronghold containing the portal and at most, a dozen Eyes will be needed to activate it.

History
The Eye of Ender was first added as an item in Beta 1.9 Prerelease 3, but had no use until the 4th prerelease, when each Eye could be placed in a portal block or used to home in on a Stronghold. Jeb's demonstrated the new uses for an Eye in his livestream. An Ender Portal within a Stronghold could be seen in the stream with two Eyes inserted into blocks.

Trivia

 * The Eye of Ender appears to have the same coding error as Sugar from 3rd person view, appearing oddly large from 3rd person view.
 * The Eye of Ender's right-click function does not work in The End.
 * The eye is a possible refrence to the eye of mordor from lord of the rings.