Originally Posted by Irimar
I suppose I could find a way for you to place a spawner. It wouldn't do anything, though.
As part of the test last night, I used a spawn egg to spawn a villager on a floating island and I spawned one in amongst the building concepts we were testing last night on the ground. The islander stayed on his island and the villager stayed around the buildings, retreating inside whenever we changed it to night. Two golems are protecting him/her/it (both the villager and the golem look like robots). The first golem was an accident
The second was made because the first was initially too far away when I made the villager.
However, any other egg-spawned mob will disappear over time. One alternative is to place an egg in a dispenser and spawn mobs on a needs basis, e.g. when someone presses a pressure pad. It will still disappear over time, but it will be there for the effect when people are there.