Small Purple Turritella Seashells - Craft Shells These small Turritella Terebra shells come packaged in a bulk bag, are easy to order and fun to use in any type of shell craft. Sizes range from .5" up to 3.5" long. Turritella terebra is a species of tower sea snail, a marine gastropod mollusk. The shells of turritellid species have whorls that are more convex and an opening which is more circular than it is in the auger shells which are similarly high-spired.  Bring the beach home with one of our unique seashells, offered in a variety of sizes. Whether it's a souvenir from a recent vacation, decorative accent for any room, or part of your coastal craft, these high-quality shells are some of the lowest prices around.