Shulker

"Adventurers should explore the outer islands of the End with care - in among the blocks of purpur hang these cannily camouflaged critters. Get too close, and their block-shaped shells pop open, allowing the mollusk-like Shulker to launch a homing projectile!"

- Marsh Davies

Shulkers are box-shaped hostile mobs found in end cities. They hide in their shell to blend in with surrounding purpur blocks and guard the city's various treasures.

Spawning
Shulkers spawn during generation of end cities, which are located on the outer islands of the End. They usually spawn on the walls of the city. They don't despawn naturally, even in Peaceful difficulty, and once killed, they don't respawn.

Drops
Shulkers have a 50% chance of dropping a shulker shell when killed. This is increased by 6.25% per level of Looting, for a maximum of 68.75% with Looting III.

Shulkers also drop 5 experience when killed by a player or a tamed wolf.

Behavior
The shell of the mob looks similar to a purpur block, blending in relatively easily to its surroundings. Inside the shell of the mob is a small yellow head with two eyes. Purple is the default color when using spawn eggs, while white is the default when using or  spawners. Spawning shulkers with other colors can be done using the command, as detailed below.

Shulkers generally remain stationary, attached to an adjacent solid block. However, if the block the shulker occupies becomes something other than air or the shulker finds itself not adjacent to any solid block, or the shell cannot open, it attempts to teleport (5 attempts per tick) to an air block within a 17×17×17 cuboid centered on the shulker that is adjacent to a solid block. If it finds no solid blocks to teleport onto (like when in the Void) it does not move.

Shulkers occasionally open their shell for 1–3 seconds to peer outside. When a target comes within about 16 blocks, it opens fully and shoots guided projectiles that follow the player, moving only along the X, Y, or Z axes and leaving trails of white particles. The projectiles can be destroyed by attacking them, or blocked with a shield. If the projectile hits an entity, it does of damage and inflicts the Levitation status effect for 10 seconds. (Levitation has no effect underwater, or on players in boats.) The shulker continues firing every 1–5.5 seconds while the target remains in range. If the shulker's target dies with projectiles still in flight, they fall to the ground.

When its shell is closed, a shulker has armor points and deflects arrows. When the shell opens, it loses this natural armor and takes damage as normal. When at less than half health, a shulker has a 25% chance of teleporting (as described above) after taking damage. When a shulker is attacked, other shulkers in the area target the attacker as well.

Shulkers don't take burning damage from lava or fire, but they drown in lava. They teleport when touched by water.

In Peaceful difficulty, shulkers exist within the world, but do not attack.

Shulkers are treated differently than other blocks. For example, mobs pathfind through them rather than walking around or jumping over them, and falling on them from a height does not produce particles. Their spawn egg also does not destroy blocks such as grass.

Shulkers can be hooked by a fishing rod. However, they cannot be reeled.

They apply Levitation II instead of I.

Dyeing
$$, shulkers can be dyed in a similar fashion to sheep. a dye on a shulker gives it the color of the dye.

Transportation


Shulkers can be moved by boats or minecarts; pushing a boat/cart into a shulker causes it to board. In a boat, the shulker retains the orientation it had before it was put in the boat. For example if a shulker is attached to the ceiling: it is possible to build a platform adjacent to the shulker and slide a boat under it, at which point the shulker moves into the boat but appears upside-down. A boat's sides block some of a shulkers projectiles (more if it is upside-down).

A shulker pushed through the exit portal gets transported to the origin in the Overworld. Since shulkers teleport when not adjacent to a solid block they must be pushed down the central pillar of the exit portal with a piston.

Data values
Shulkers have entity data associated with them that contain various properties of the mob.

Shulker bullet
A shulker bullet is a guided projectile that is shot from shulkers, and they follow the player along the X, Y, or Z axis and leave trails of white particles.

The shulker's projectiles also have entity data that control its movement.

The bullet can be destroyed by hitting it with a sword, shooting it with an arrow, or blocking it with a shield.

Trivia

 * The word "shulker" is a portmanteau (combination of multiple words) of "shell lurker".
 * All shulker named 'Dinnerbone' or 'Grumm', the mob flips upside-down, revealing a spiral pattern on the base. This appears to also lift the shulker the same height as a pressure plate.
 * Placing a gravity-affected block such as gravel or an anvil on the shulker lifts while the shulker opens its shell, and after some lifts the block drops as an item.
 * Shulkers can attack each other, in which case they shoot fully guided bullets at each other, but are unaffected by levitation when hit. The normal teleportation habits apply during shulker vs. shulker battles. This can be advantageeous because the shulkers ignore the player and makes them easier to defeat.
 * By using commands, they can be made to be part of a team to attack other teams and can be used as defense mobs. In that case, it doesn't attack its teammates, but targets most hostile mobs without provocation.
 * Shulkers have exactly the same size as a full-sized block, but their model appears to be just a tiny bit smaller.
 * When standing on a shulker's shell, you can sneak and not fall off, like with other blocks. If the shell is opened sideways, this can simulate a vertical slab, which you can still stand and sneak on without falling (until the shell closes).
 * If given the invisibility effect, only the shulker's shell becomes invisible. This is different to most other mobs such as armored mobs and saddled pigs, where the living part of the mob turns invisible with the outer areas remaining visible.
 * An arrow shot at a shulker's closed shell bounces off of the shell, similar to when arrows are fired at players in creative mode.
 * When teleporting or spawning, shulkers reorient themselves depending on the side of the block that they are attached to. This means that shulkers may appear sideways or even upside down.
 * Shulker spawned with appear to have a white shell instead of a purple shell.
 * In the game's texture files, the shulker bullet is named "spark.png".
 * Shulkers teleport when a falling block such as sand falls on them. If spawned with no AI and sand is dropped on them, they darken in color and the block hops continually. If with AI and sand is dropped on them and the shulker has nowhere to go, it suffocates.