Shulker shells are items dropped by shulkers, which are unique hostile mobs found in the End dimension of the game Minecraft. When defeated, a shulker can drop one or two shells, which players can collect. These shells are used primarily to craft shulker boxes, a special type of storage container that retains its contents even when broken. Shulker boxes are highly valued for their portability and organization, making them popular among players for inventory management. The ability to stack shulker boxes allows for efficient storage solutions, enhancing gameplay and exploration in the vast world of Minecraft.