No clue, but unless someone knows what it is off the top of their head, we need some more info to help you. So it's hollow all the way through? In the first, grayish, picture, are those 2 pinholes that go in - all the way to center? do one of the holes line up with the one in the reddish picture?
Also, was it found with other artifacts, in a privy, home site?