the bony or partly cartilaginous rod connecting the eardrum with the inner ear in birds and in many reptiles and amphibians
the bony central axis of the cochlea (spirally coiled hearing organ) of the ear
the central column or axis of a spiral shell (e.g. of a snail)
the axis of the spore-bearing capsule in mosses and some liverworts
columellar adj
columellate adj
[scientific Latin columella, from Latin, dimin of columna column]