The sturdiest shell in our collection, the Turbo Tune Call, is made from a Turban Shell, and it's sound imitates the cry of the Loon. See the rough textured image provided. It contains only one pitch hole.The Turbo Tune Call Whistle is an entry level seashell musical wind instrument; is the perfect whistle for developing the skills used for learning to play a more complex instrument like the Screw Shell Flute.