Allay

java

The allay is a passive flying mob similar to the vex.

Pillager outposts
Allays can be found surrounding pillager outposts, confined inside dark oak cages. 1 to 3 allays can spawn in each cage.

Woodland mansion
Allays can also spawn inside jail cells within woodland mansions. 1 to 3 allays can spawn in each cell.

Behavior
Allays fly around aimlessly until with an item. It will appear to hold that item in its hand, and then will scan the area around the player for instances of that same item, where it will then return it to the player. If interacted again with an empty inventory slot, the player will get the item back. Allays can pick up items that are 15 blocks away from them.

They have a slot in their inventory, allowing them to carry 64 stackable items at once. It can carry 1 non-stackable item, excluding the one that it holds. If a note block is being played, the allay will instead return items to that particular note block for up to 30 seconds with a vibration particle reaching the allay.

If the allay has items in its inventory and is killed, it will drop all the items that it had.

Allays can pick up similar variants of the item given to them. (If you give it a certain colored wool, it will also pick up different colored wool)

They have a luminescent texture, allowing allays to be seen clearly in the dark.

Even though pillagers have captured the allay, they will not attack it.

Sounds
Currently, allays make no idle sounds. If hit, they make the same sounds as the player.

Trivia

 * Despite not having any connection with warden and sculk sensors, it has a similar property when it interacts with a vibration signal when a note block is being played.
 * Despite their ghostly appearance, allays aren't considered undead mobs, similar to ghasts and vexes.
 * Unlike vexes, allays can't phase through blocks.