phragmocone
/ˈfræɡməˌkoʊn/
noun
- The internal, cone-shaped, chambered part of the shell in certain cephalopods (such as squids, cuttlefish, and extinct ammonites) that helps with buoyancy control.
- In cuttlefish, the phragmocone is filled with gas and liquid to help the animal float at different depths.
- Scientists study the chambers of the phragmocone to learn about the life history of extinct cephalopods.
- The fossilized phragmocone of an ancient ammonite was carefully extracted from the rock.