I recently got a lead on identifying some of the pyritized fossil Goniatites from Morocco that I have. I purchased some of these fossils from a dealer but they did not come with any labels or locality information. All they gave me was "Mrakib". So they have languished in a corner for a year or so while I put searching for information on the back burner. Thanks to a comment on a thread on Facebook though, I was re-inspired. The commenter posted a picture of several different fossils and had them labelled with names. One, named Prionoceras, appeared to match a specimen that I had and so I punched the name into Google Scholar to see what came up. Lucky for me a paper was listed that was available to the public via Researchgate.net (you can view and download .pdf documents as long as the author allows the public, though you have to sign up with the site):
"Middle Famennian (Late Devonian) ammonoids from the Anti-Atlas of Morocco. 1. Prionoceras", Korn, D. & Bockwinkel J., Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 272/2, May 2014, pgs. 167-204
From that paper I found this figure (Fig. 21) which appears to match my fossil and is called Prionoceras lentis.
And here is the specimen that I am now calling Prionoceras lentis
Right side (note that the constrictions are curved on this side but are straight on the left side)
In addition, the aforementioned paper indicates that this particular species comes from the "Platyclymenia beds, Madène el Mrakib" which are Upper Devonian (Famennian stage) in age.