Minecraft wiki entry for Shulker, associated text: Entity data
Tags common to all entities[show]
Tags common to all projectiles[show]
 Steps: How many "steps" it takes to attack to the target. The higher it is, the further out of the way the bullet travels to get to the target. If set to 0, it makes no attempt to attack the target and instead uses TXD/TYD/TZD in a straight line (similar to fireballs).
 Target: The UUID of the target of this shulker bullet, stored as four ints.
 TXD: The offset in the X direction to travel in accordance with its target.
 TYD: The offset in the Y direction to travel in accordance with its target.
 TZD: The offset in the Z direction to travel in accordance with its target.