The shape of the shell is a basic characteristic for the description of the Conus species; sometimes, when the colour pattern and the animal lack - such in fossil -, it is the only source.
For some author the shape of the shell was or is still the key for a generic and subgeneric subdivision. At the moment, I  consider the Family Conidae is represented only by the unique Genus Conus; I hope however for a revision of the Genus since the evident  interspecific variability.
For a closer examination, it's useful to subdivide the shell in four parts: the Body Whorl, the Spire, the Shoulder and the Aperture.