This particular specimen,
is from the order Phacopida,
The seller, Stones & Bones, lists it as being from the
Silurian, but most authorities say this species
is from the mid ordovician.
This specimen is quite a bit larger than the
found in the growth series, and comes from Morocco rather than Utah.
It is typical in Morocco to split a promissing rock open to see what's inside. This often splits the specimen so that a lot of
repair is needed.
Sometimes, however, it is left in this state and sold as is. The result could hardly be described as
but, as clearly shown by the pictures on this page, it has a lot of potential for stereoscopic imaging!