phragmocone
/ˈfraɡməkəʊn/(also phragmacone) Zoology
noun
The chambered part of the shell in some cephalopods; especially the conical chambered internal shell of a belemnite.
Origin
Mid 19th century; earliest use found in Richard Owen (1804–1892), comparative anatomist and palaeontologist. From phragm- + -o- + cone.