Hecticoceras svevum ammonite fossil collected from the Jurassic Oxford Clays of Oxford. Hecticoceras is an extinct genus of ammonite which can be found in Mid to Upper Jurassic sediments. They were nektonic carnivores which fell to the sea floor upon death. These examples were preserved within an oxygen starved deep marine shelf which gave rise to the Oxford Clay Formation. Each specimen has a smooth evolute shell, some of which exhibit very feeble ribbing. They measure approximately 1.5 cm in diameter and are supplied in a small plastic bag with an information label.