This trilobite is from Lucas County, Ohio. This trilobite is probably my favorite because it is the one I find the most in the Louisville, Kentucky area. The creature lived in the Paleozoic Era in the Middle Devonian Period (around 395 million years ago).
This one was probably found in Silica Shale. It is from the phylum Arthropoda and was called Phacops rana (I have also seen specimens from Ohio referred to as Phacops rana crassituberculata). This trilobite might also be known by the name Eldredgeops rana. The fossil trilobite must be found quite a bit in Pennsylvania was well since it is their state fossil.
This specimen is enrolled sort of like the modern day isopod Armadillidium ("pill bug") does. Also note the large compound lens eyes. This type of eye is called Schizochroal allowing the trilobite to have 360 degree vision. Since the creature had this ability I am guessing it was preyed upon by something (maybe a shark).
Thanks to an anonymous friend for the images.