Ghost Armor

The Ghost Armor is a Hostile Mob found commonly in strongholds and Nether Fortresses.

Behavior
At first sight, the Ghost Armors may appear to be basic Iron Armors dropped by another player, but when a player gets close to them, they will mobilise and chase the player. Even though they does no damage at all, they will take control of any player and drive him/ her into hazards or other Hostile Mobs.

Combat
Like Floating Swords, Ghost Armors takes damage when on soul sand, but other than that, they can ONLY be damaged by the Ghostbuster Sword. They will sink into water and lava just like Iron Golems, so if you see a suspicious armor on the ground, dig a 2 block deep pit, fill it with water, then approach it. When the Ghost Armor starts chasing you, just lure it into the pit and it will be trapped. Dig around the pit if you want to proceed.

If the Ghost Armor succeed in taking control of you, keep on pressing WASD and Space until you break out.

Zombies and Skeletons Armor
There is a 10% chance that a Zombie or Skeleton in Strongholds will spawn possesed by a Ghost Armor, in that case, they will be faster and does more damage. Very dangerous in conjuntion with a Spider Jockey (or Cave Spider Jockey).

Nether and Aether Ghost Armor
If you're in the Nether, you may see a Golden Ghost Armor in Nether Fortresses, it behaves the same way and like it's overworld counterpart, may posses a Zombie Pigman to give boosts.

A Gravitite Ghost Armor can be seen in the Aether as well, however unlike the Overworld and Nether versions, they won't posses any mobs or player, and will attack them like a Zombie would.

Trivia
1. Despite being made of Rusty Iron, Ghost Armors share the same texture as Iron Armors.