When the x-coordinate or z-coordinate is equal to 2^(2^n)-1 (where n is an integer), collisions extend beyond the boundaries of (0, 0). When both the xz-coordinates satisfy this condition, collisions extend in two directions.

 
When any of Shulker's xyz axes is at ±1, 7, 63, 511, 2047, 1048575... (possibly more), collision detection expands outward from the origin of that axis. Additionally, when multiple axes apply simultaneously, collision detection extends outward on all those axes simultaneously.

When the player touches the collision, it gets down, and when the item touches it, it bursts out.