This divot tool is made from Walrus Oosik, also called baculum or penile bone. While it seems like a very uncommon item, the fact is that most male mammals have baculum including raccoons, otters, weasels, seals, and even dogs and cats. The term Oosik comes from Alaska where it is used to describe the baculum of large mammals like walrus, seals and whales. Native Americans often used Oosik as clubs or tool handles, especially walrus oosik which grows about 2 feet long. The material is usually brown in color and takes a very nice polish.
This particular piece was made from an unusually solid area of bone and most of the surface has a very fine grain which allows it to take a very smooth, glass-like polish. At just under 2-1/2" long and 7/8" wide it has a nice compact feel and heft that would be relatively unobtrusive in one's pocket.