This is a mouth plate of the extinct lobe-finned lungfish, Ceratodus. It's Late Cretaceous in age and comes from the Kem Kem Beds near Taouz, Morocco. The closest living relative of Ceratodus is the Queensland lungfish (Neoceratodus forsteri), of North-eastern Australia, which is considered a ‘living fossil’.
The Kem Kem Beds are famous for yielding a diverse, Late Cretaceous, vertebrate assemblage including fish, reptiles and dinosaurs such as Spinosaurus. These fossils
are found in a thin bed that outcrops around the edge of a large plateau near Taouz, Morocco. Local miners collect these fossils by digging narrow tunnels by hand into this plateau following the layer.
A paper on this assemblage can be found at: Vertebrate assemblages from the early Late Cretaceous of southeastern Morocco: An overview
One of the tunnels dug into the Kem Kem beds by local miners following the productive fossil beds.