Ammonoidea

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An ammonite, a subclass of the Cephalopoda class, is showcased in the teaching collection of the Department of Invertebrate Paleontology. The living marine mollusk group known as cephalopods are characterized by their tentacles attached to a cone-shaped body. Derived directly from Greek words, the term "cephalopod" means "head-feet." Most fossil cephalopods developed a calcareous shell around their conical bodies made of calcium carbonate. The shape of these shells can be straight, curved, or coiled. As cephalopods grow, new chambers are sealed off in their shells with the body connected by soft tissue through a thin tube called the siphuncle. Today, living cephalopods include cuttlefish, squid, and octopus, but only the nautilus has a coiled shell as described in "Phylum Mollusca, Class Cephalopoda" (David and Mapes 1996).