This is an excellent specimen of Onnia superba from the Ordovician of Morocco. This trilobite was found in the concretionary Diacalymene zone, not the limestone layers where almost all specimens of this type has been found. This inflated Trinucleid trilobite is wonderfully articulated and exhibits superb detail. The pitted margin of the cephalon is well preserved, and the long, thin genal spines are clearly defined. The individual thoracic segments are easily seen, and the wide, triangular pygidium is also present. The dark brown trilobite contrasts nicely with the light-colored matrix. The large bug is beautifully displayed in the center of the concretion, which also has a partial Diacalymene preserved. This is a beautiful, rare example of Onnia in a large concretion. (Second photo shows the concretion when both halves are put back together.)
A Certificate of Authenticity from EXTINCTIONS is included with this specimen.