At one of our shows, a little girl called this our 'unicorn' shell. In truth, it's probably a Sharp Hornsnail, a species of mollusc common in Lake Erie, where the original of this shell was found.
Our version was molded from that original, cast in solid sterling silver, and polished to a high shine.
The shell is roughly 3/4 of an inch (20mm) long and 1/4 inch (7mm) in diameter. It hangs on a delicate 18 inch (46 cm) chain.