Allay

java

An allay is a passive mob able to fly, similar to the vex, whose function is to assist players with the transport of items.

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 have a luminous texture, allowing allays to be seen clearly in the dark. They fly around aimlessly until with an item. It will appear to hold that item in its hand and will scan the area around the player for exemples of that same item, where it will then return it to the player. A player will get the item back if an allay is interacted again while the player has an empty inventory slot. Allays can pick up items that are up to 15 blocks away from them.

An allay has only 1 slot on its inventory, allowing it to carry 64 stackable items at once. An allay can carry a single non-stackable item, excluding the one that it holds. If a nearby 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.

Allays drop all the items that they had when they are killed.

Allays can pick up similar types of the item given to them. If a player gives it a certain colored wool, it will also pick up different colored wool.

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