Mob spawners

Mob Spawners are blue-ish fiery cages found within Dungeons. When first found, there will be a hostile mob (i.e. zombies, spiders, etc.) spinning around within. After some amount of time the mob within will pop out in a large puff of smoke, and the generation process will continue. (If you are on Peaceful mode, a hostile mob will be in the cage, but the mob never comes out.) The mob usualy spawns when the creature within is spinning very fast. When the mob spawns, it will slow down and start again.

Upon collection of the cage and re-placement, it will spawn pigs. In the future, it will possibly be able to spawn sheep. However, there has never been a creeper spawner, and possibly never will be.