A parietal callus is a feature of the
shell
Shell may refer to:
Architecture and design
* Shell (structure), a thin structure
** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses
** Thin-shell structure
Science Biology
* Seashell, a hard o ...
anatomy of some groups of
snail
A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class G ...
s, i.e.
gastropods. It is a thickened
calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines.
In zoology
''Calcareous'' is used as an a ...
deposit which may be present on the parietal wall of the
aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane.
An ...
of the adult shell. The parietal wall is the margin of the aperture and part of the wall of the body whorl that is closest to the
columella
Lucius Junius Moderatus Columella (; Arabic: , 4 – ) was a prominent writer on agriculture in the Roman Empire.
His ' in twelve volumes has been completely preserved and forms an important source on Roman agriculture, together with the ...
. The callus is often smooth and glossy, but can also be decorated with raised ribs or wrinkles.
This feature is found in such marine families as
Ranellidae (pictured),
Cassidae,
Nassariidae
The Nassariidae, Nassa mud snails (USA), or dog whelks (UK), are a taxonomic family of small to medium-sized sea snails, marine gastropod mollusks in the clade Neogastropoda.
"Dog whelk" also refers to '' Nucella lapillus''.
Shell descripti ...
,
Ringiculidae and others. It is also found in some families of land snails, terrestrial
pulmonates.
See also
*
Gastropod shell
The gastropod shell is part of the body of a Gastropoda, gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium s ...
*
Aperture (mollusc)
References
Gastropod anatomy
Mollusc shells
{{gastropod-stub