Hermit Crab Changing Shell Set for medium sized Hermit Crabs. Set of 18 Hand Selected Turbo Shells with Smooth, Round openings ranging in size from 1" to 2" with opening sizes from 1/2" to 1". Hermit Crabs need plenty of shells to choose from as they grow. This set is sure to make your Hermie happy. You will receive a hand selected assortment beautiful seashells with smooth openings. Natural variations in coloring are normal. Shells may be substituted as availability dictates.