[1][2][3] They are almost exclusively known from their hard external structures (alternatively referred to as a theca, periderm or test), which were pyramidal in shape and made up of numerous lamellae.

The conulariids are fossils preserved as shell-like structures made up of rows of calcium phosphate rods, resembling an ice-cream cone with fourfold symmetry, usually four prominently-grooved corners.

[4] New rods were added as the organism grew in length; the rod-based growth falsely gives the fossils a segmented appearance.

The prevailing reconstruction of the organism has it look superficially like a sea anemone sitting inside an angular, hard cone held perpendicular to the substrate.

But due to their calcium phosphate composition, their crystal structure, and their extreme age, these pearls tend to be rather unattractive for use in or as decorative objects.