conularia

from The Century Dictionary.

• noun A large genus of fossil thecosomatous or shelled pteropods, of the family Thecidæ, or typical of a family Conulariidæ, extending from the Silurian to the Carboniferous. C. elongata and C. sowerbyi are examples. Some of these mollusks are nearly two feet long. They have a four-sided shell, whose apex is partitioned by narrow close-set septa resembling a nest of cones or pyramids placed one within another, whence the name of conein-cone.