Eoharpes, Ordovician trilobite fossil. Trilobites were arthropods that fed as they crawled on the seabed. They lived between 500 and 300 million years ago and are now extinct. This specimen dates from the Middle Ordovician, and was found in Wales in the Llanvirn Series, in the Llanfathteg Formation. Cefn-maen-llwyd, Whitland Dyfed, UK. This is a complete individual. It is part of a group of trilobites that have a unique cephalic region structure: a broad flat brim that surrounds not only the cephalon, but extends back as far as the pygidium, so that the thorax and pygidium are contained. This may have prevented the trilobite sinking into soft sediment, or acted as a hydrofoil when in motion. The eyes consist of only a limited number of lenses and are positioned centrally either side of the glabella. This specimen is 1.1 centimetres long.