Belemnites were marine cephalopods, closely related to modern squids and cuttlefish, that lived during the Mesozoic Era, from 240 to 66 million years ago. Fossils of belemnites, such as this guard specimen, are commonly found in Mesozoic marine sediments and serve as valuable index fossils for dating and correlating geological strata. These creatures, along with other marine invertebrates such as ammonites, went extinct during the Cretaceous-Paleogene (K-Pg) mass extinction event around 66 million years ago. Comes with one belemnite fossil displayed in an acrylic display. Belemnite fossil size: .75"-1" Acrylic case: 1 ⅝" x 2 ⅛" Includes a detailed info card.