This is a large enrolled trilobite. It is a complete Isotelus maximus from Ohio. This type of trilobite is the State Fossil of Ohio. This specimen is tightly enrolled - the tail is tucked right under the head (see second photo). The front, display side and even the back side shows only slight compression - the bug is inflated a full 1.3 inches!. This is a very fine enrolled example of this classic US trilobite.
This fossil was collected and obtained legally, and is also being sold legally.