Shulker shells are items in the game Minecraft that drop from Shulkers, which are unique hostile mobs found in End Cities. When defeated, a Shulker has a chance to drop one or two shells. These shells are used primarily to craft Shulker Boxes, which are special storage containers that retain their contents even when broken. Shulker Boxes are highly valued for their portability and organization, making them popular among players for inventory management. To craft a Shulker Box, players need one chest and one Shulker shell for each box they want to create.