Connecting rings are in general poorly calcified and may expand as siphonal bulbs into the chambers where not restricted by septal necks.

[3] As with all shelled cephalopods, plectronocerids had a tube called a siphuncle, which let them fill the chambers of their phragmocone with gas instead of water, thus controlling their buoyancy.

The Plectronoceratida gave rise in the Late Cambrian (early and middle Trempealeauan) to the other three plectronoceratoid orders, the Ellesmerocerida and Protactinocerida and Yanhecerida.

The Plectronoceratidae gave rise to the other ellesmerocerid families, including the Upper Cambrian exogastric Balkoceratidea, and with remote possibility to the Discosorida.

Plectronocerids were probably benthic animals that crawled along the bottom in search of food or safety, facing downwards, with the shell carried above.