This is a very large specimen of Isotelus mafritzi from the Ordovician of Canada. This outstretched trilobite is wonderfully articulated and exhibits fine detail. The small, crescent-shaped eyes are easily seen, and the short genal spines are quite evident. The thick-shelled exoskeleton is very well preserved. The bug has outstanding color and contrasts very well with the lighter-colored matrix. The trilobite is almost perfectly centered on the rectangular plate of limestone. This is a very collectible example of a very large Isotelus mafritzi from Ontario.