"Mother of Pearl (known scientifically as Nacre) is the inside body material produced by certain mollusks such as clams and oysters. It is the same material that makes up the outside skin of a pearl. It has many positive properties as a fish catcher, particularly among them that it is very durable and iridescent. While native Pacific Islanders long ago learned the value of the Mother of Pearl spoon, it was in the nineteenth century that American tackle makers caught on to the idea. Most tackle makers offered their version and since the material is very difficult to work with, few marked them. So what you have likely dates from 1900-1920 and is worth $10-$20. It's a great collectable and will still catch fish!"