This is an unusual type of Ordovician trilobite. It is a large Illaenus tauricornus from St. Petersburg, Russia. This specimen was recently acquired from a major trilobite collection. Most Illaenus have rounded genal angles, and do not have genal spines. This type has long, curving genal spines on each side - this specimen has these spines preserved and are easily seen. The trilobite itself is complete and very inflated. The natural caramel coloration is striking, and the detail is excellent. The large eyes also display prominently. The trilobite is nicely showcased on the small block of limestone. This is a very displayable example of this spiny Illaenus trilobite.