When the animal was alive, the interior of the shell was divided into chambers which were partly filled with air for buoyancy.

The soft parts of the body have not been preserved in the fossils known, but it is probable that Hildoceras bifrons was a predator and caught its prey with tentacles that projected from its aperture.

[1] Fossils of Hildoceras bifrons have been found in North Africa, the Caucasus Mountains, Europe and Eastern England.

Their closest living relatives, the nautiluses, are able to swim because their weight does not exceed their buoyancy, their apertures are suitably orientated and they have sufficient stability to maintain a vertical position.

Careful examination of Hildoceras bifrons and some other ammonites makes it seem unlikely that they had a pelagic lifestyle and it is believed that they were primarily benthic animals living on the seabed.