Flukers Hermit Crab Growth Shells Bag of 3 small size Fluker's hermit crab growth shells Place in your hermit crabs' tank to allow them to change as they grow Shells come in a variety of colors and patterns to add visual interest to your pets' home Always select shells that are larger than the ones your crabs currently reside in Keeping a variety of sizes of shells in your hermit crabs' enclosure promotes healthy, natural development.