Paradoxides mureroensis, Cambrian 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 Cambrian, and was found in Murero, Zaragoza, Spain. This complete individual specimen is partly distorted. It has very long genal spines, the pleurae terminate in long spines, and it has a small shovel-shaped pygidium. This specimen is 3 centimetres long.