Offered in this lot are two nicely preserved fossils. This first is a Preserved Trilobite Fossil. Trilobites form one of the earliest-known groups of extinct marine arthropods. By the time trilobites first appeared in the fossil record, they were already highly diversified and geographically dispersed. Because trilobites had wide diversity and an easily fossilized exoskeleton, they left an extensive fossil record. The study of their fossils has facilitated important contributions to biostratigraph, paleontology, evolutionary biology, and plate tectonics. Trilobite fossils are found worldwide, with thousands of known species. Because they appeared quickly in geological time, and moulted like other arthropods, trilobites serve as excellent index fossils. Also included in this lot is a Polished Goniatite Ammonite Fossil. This ancient creature swam in tropical oceans during the Devonian, about 400 million years ago. Ammonites belong to the cephalopod class, cousins of the present squid and octopus. Goniatite ammonites were named after their wavy suture lines that decorate the out shell in beautiful patterns. These sutures outline the chambers or septa that were used for regulating buoyancy allowing the animas to quickly change depths in the ocean. In Medieval Europe Ammonites were thought to be petrified snakes. They were called "snakestones" or "serpent stones". Ammonites were said to be evidence for the actions of St. Hilda and St. Patrick - who drove the snakes out of Ireland. In ancient times, traders would carve the face of a snake into the wide end of the ammonite fossil and sell them to the public. These fossils are in well preserved condition, the trilobite is 4.25"L x 2.75"W x1.75"H; the goniatite ammonite is 3.5" diameter, 1.75"H at its thickest.