Here is a top quality example of the Harpetida trilobite Scotoharpes sp. from Morocco. It has a very dramatic "head shield" which is often interpreted as a mechanism to help it stay on top of a soft ocean floor. This preglabellar ring (head shield) is covered in many sensory pits which may have held hairlike features when the trilobite was alive.
The preparation on this specimen is second to none. You probably won't find a nicer specimen of this species out there.