columella

noun7

1. •
   Any of various small structures in plants or animals that are columnar in shape.
2. •
   The skin at the end of the septum which separates the nostrils.
3. •
   In birds, reptiles, and amphibians, the small bone which carries vibration from the tympanum to the inner ear.
4. •
   In gastropods, the structure that extends down the middle of the whorls of the shell.
5. •
   The structure at the center of the calyx where the septa join together.
6. •
   The central sterile portion of the sporangium in various fungi.
7. •
   A rod-shaped reinforcing element of the sexine layer of a pollen grain.