Beating a special mine spawns a random shimmering key from the mine crafter block.
Beating a normal mine has a 1 in 10 chance to spawn a shimmering key, this gives the player the possibility to obtain keys more than every 5th mine.
Alternatively, a player can obtain a specific Shimmering Key with /give @p minecraft:shimmering_key[minecraft:instant_room={"structure": <structure>}], where <structure> is one of the structure presets created for this snapshot.
Shimmering keys can be used on a shimmering door, which opens a menu. If the given key is valid and there is space behind the door to spawn the room it is trying to create, it then spawns a new room based on the key provided.
The keys tooltip shows the player which room type is created upon unlocking a shimmering door.
When a new shimmering key is spawned from the mine crafter block, it comes with one of these structure presets in its minecraft:instant_door component:
👁 Image Inside of this house is a lectern saying "Dear Bob I hope you are doing well! I heard some disturbing news and I wanted to ask what happened to".
Issues relating to "Shimmering Key" are not maintained on the bug tracker because it is an April Fools' joke, and is therefore not in the newest stable version or snapshot. Issues reported there are closed as "Invalid".
In the creative inventory, the Shimmering Key is in the Functional Blocks tab, despite being an item.
Manually spawning a new Shimmering Key item with a valid minecraft:instant_room component allows the player to create a new room from a shimmering door, as long as there's enough space to place the room. The room created is entirely dependent on the value of the component; without it, the key does not work.