I am not certain I am following your line of reason.

The columella of a turritella shell is conical—so it has one thicker/larger end, and proceeds down to a thinner pointy end.

The specimens you show are 1) of equal diameter all along their length; or 2) are CARVED from another material. The carved specimens may represent turritella columella ornaments, but they appear to be imitations.

In antiquity, there were both columella beads and glass imitations of them, that I believe may have been derived from (and inspired by) chank shell columellas. I show these in my paper on trade bead inspirations, for the Istanbul Bead Conference of 2007.

Jamey