In this Phacopida Trilobite fossil from Morocco, the ancient organism's ridges and sectioned body are clearly visible. Dating back to the lower Ordovician to the upper Devonian periods, 488 to 359 million years ago. Trilobites were the first arthropods on earth and were the precursors of today's insects, spiders, and crustaceans. The name trilobite means “three-lobed” and refers to the pair of furrows along its length that divides the body into three sections. Includes certificate of authenticity.