UMBILICUS

Umbilicus

The umbilicus of a shell is the axially aligned, hollow cone-shaped space within the whorls of a coiled mollusc shell. The term umbilicus is often used in descriptions of gastropod shells, i.e. it is a feature present on the ventral side of many snail shells, including some species of sea snails, land snails, and freshwater snails.

The above text is a snippet from Wikipedia: Umbilicus (mollusc)
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umbilicus

Noun

  1. navel
  2. hilum
  3. A depression or opening in the center of the base of many spiral shells.
  4. Either of the two apertures in the calamus of a feather.
  5. One of the foci of an ellipse or other curve.
  6. A point of a surface at which the curvatures of the normal sections are all equal to each other.
    A sphere may be osculatory to the surface in every direction at an umbilicus.
  7. An ornamented or painted ball or boss fastened at each end of the stick on which manuscripts were rolled.


The above text is a snippet from Wiktionary: umbilicus
and as such is available under the Creative Commons Attribution/Share-Alike License.

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