Sekioida

Sekioida is a term that refers to a specific type of ancient cephalopod fossil. These fossils are primarily found in the Devonian period, dating back approximately 419 to 359 million years ago. Sekioida are characterized by their coiled, chambered shells, which exhibit a distinct helical or spiral arrangement. This coiled structure is a key feature distinguishing them from other nautiloids and ammonoids, which also possessed chambered shells.

The internal structure of sekioid shells typically shows a series of chambers separated by walls called septa. These chambers would have been filled with gas or fluid, allowing the organism to control its buoyancy and depth within the ancient seas. The animal itself would have inhabited the outermost, largest chamber, using a siphuncle, a tube connecting the chambers, to regulate the internal environment.

Fossils of sekioida are important for understanding the evolutionary history of cephalopods and the paleoecology of Devonian marine environments. Their presence and distribution can provide insights into the biodiversity and environmental conditions of that era. While not as widely known as some other fossil groups, sekioida represent a fascinating branch of early cephalopod life.