siphuncled

Updated: May 27, 2025

At the end of the Mesozoic the entire tribe of ammonites became extinct. Like the squids and cuttlefish, of which it was the prototype, it had an internal calcareous shell. This consisted of a chambered and siphuncled cone, whose point was sheathed in a long solid guard somewhat like a dart.

William Harmon Norton - The Elements of Geology