 Because some of the other highly derived cheirurid trilobites, such as the Devonian "Crotalocephalus" and "Cybelloides" of the Ordovician, have been interpreted as being swimmers or plankters, the species of "Deiphon" have been popularly thought of as being planktonic, as well.Mostly, it is due to the idea that its globular glabellum was filled with fat or oil, thus, serving as a balloon to keep it in the water column, and its elongated pleural lobes serving to keep it from sinking.If it were a nektonic or planktonic trilobite, the spherical glabellum, coupled with its rib cage-like pleural lobes and spine-like cephalon cheeks would have presented serious impediments to its hydrodynamic ability, and would have been either a drifter, or a very leisurely swimmer, feeding on phytoplankton, or slow-moving zooplankton.