OK, so asking on an artifact forum a couple guys think the "threaded hole" is an actual fossil from what they called a crinoid, sea "animals with rough, spiny surfaces and a special kind of radial symmetry based on five or multiples of five."
http://www.kgs.ku.edu/Extension/fossils/crinoid.html
After re-examining the hole I determined the rings actually do not spiral down but are single continuous rings which would support the idea of them being a crinoid. Pretty dang cool though!!