For the curious, this years image contains fossils from four time periods. The star, red and blue ornaments are Ordovician crinoid stem pieces of Madison, Indiana. The trunk is an unidentified crinoid stem from the Silurian Waldron Shale of Clark County, Indiana. The tree body is an unidentified horn coral from the Devonian Jeffersonville Limestone of Clark County, Indiana. Last, the yellow ornaments are unidentified crinoid/blastoid stem pieces from the Mississippian Period limestones of Crawford County, Indiana. All the fossils have had their colors modified to match a real Christmas tree.
See this April 2010 blog post on the Ordovician crinoid pieces for their identifications.