Asaphiscus wheeleri Meek.
Complete outstretched specimen on dark grey shale. Black exoskeleton. At some point after buried the consolidated shale has undergone mineralisation and cubic pyrite crystals have gown underneath the trilobite and punctured the exoskeleton in several places. very unusual preservation for this formation.
Middle Cambrian, Wheeler Formation.
Millard County, Utah, USA.
Trilobite : 5 cm long.
