Wholesale Small Pearly White Spurred Turban Shells for Small Hermit Crabs and seashell crafts, astrea calcar, measuring between approximately 3/4 inch to 1-1/4 inches (some may be over or under this size range). Calcar means spur; the outer shell has a spiral of blunt bumps and spikes and is usually encrusted and thus well comouflaged, on the rocks. The outer layer of the shell has been removed (pearlized) using a chemical process revealing a pearly white layer. Shell opening is smooth and its pearly shell is thick, flattened conical shape. . These are found in the Indo_Pacific Region.