Shulker

Shulkers are box-shaped hostile mobs in Minecraft, commonly found on the walls of end cities and end ships. They hide in their shells to protect themselves and blend into their surroundings, their shell colors resembling purpur blocks, making them difficult to spot. When a player gets close, a shulker opens its shell and fires homing bullets that inflict levitation. They are the only source of shulker shells, used to craft shulker boxes. Shulkers have armor when their shell is closed, deflecting arrows, but lose it when open. They can be moved by boats or minecarts and do not despawn naturally, even in Peaceful mode. There is a chance that a new shulker will spawn when hit by a shulker bullet.