A couple of years ago I purchased a few the mud ball trilobites from a member on the Fossil Forum site. There wasn't much information on who, what or where they came from (other than Morocco) but they make for nice display specimens. Most of the specimens that I've seen for sale are loose, single trilobites that have poor preservation (such as these posted on E-bay). There are a number of different names associated with these trilobites as well with most being called "Calymene" or Flexicalymene". The pieces I purchased were whole nodules that had been cracked open.
First up are a couple of pictures of the exterior of the nodule they fossils are found in.
They have to repair them once broken and this particular one had a coating of another clay to make it look more homogenous and not fractured. I washed it off in favor of the natural look.
Inside is a nice positive and negative of a large Flexicalymene type trilobite. No additional paint or touch up was applied to the fossil, this is exactly how it looks.
After a quick search of the interwebs I found an answer to the species and location of these mud trilobites:
Tazzarine des Aït-Atta, Tarhbalt (Maïder)
late Ordovician - Ashgill (lower) (Hirnantian stage of ICS)
Ktaoua clay and sandstone group
upper argillite formation
Thanks to "Pirhana" a member of the Fossil Forum site for posting the useful info.