columella
From ZooTerms (Dictionary of Invertebrate Zoology)
pillar or column.
columella (noun; Latin diminutive columna, column): 1. A rod,
2. (Cnidaria: Anthozoa) The central skeletal mass of many corals.
3. (Mollusca: Gastropoda) The solid or hollow pillar of a univalve shell around which the whorls are arranged.
4. (NEMATA) A structural unit of the female uterus composed of columns of cells believed to form the egg shell; prouterus; quadricolumella; tricolumella; oogenotop
See also: crustaformeria.