White Pearl Trochus Shells in packs of 25.  Pearl trochus shells are a a cone shaped white seashell, Trochus niloticus, or top shells - trochidae. These white pearlized trochus shells measure approximately 2-1/2 inches in size. The outer layer was removed using a chemical process, revealing a beautiful white pearly layer.  These shiny white shells are used in seashell decor by adding them to glass containers or baskets and are also used as accents on seashell wreaths and mirrors.  The Tectus niloticus, which is valued for its nacre or mother of pearl layer, was traditionally made into items such as pearl buttons and jewelry.