Flexicalymene Trilobite Mystery Piece

Here are some pictures of fossilized Flexicalymene trilobite remains from the Ordovician Period.

What I am trying to figure out is what is the blackish boom-a-rang shape in between the thorax segment and cephalon pieces? Maybe it is not even part of this trilobite since it is a different color.

It was found in Carroll County, Kentucky in the Kope Formation.

Isotelus Pygidium and Hypostoma

Here are two pieces of Isotelus Ordovician Period trilobite. I think my cousin found this in Carroll County, Kentucky in the Kope Formation.

I should have gotten some sort scale on the image. What attracted me to this fossil was the fragment of line texture still preserved on the hypostoma ("mouth plate" or food scoop).