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In the alive animal the
shell
is covered with a thin sheet of tissue called
periostracum.
In some species, particularly in the ones with complex tent patterns, the periostracum is
made of a thin yellowish film, while in other ones it’s thick, brownish, opaque and
provided with little tufts often following the spires and the ridges of the shell
itself.
The shell can be divided into two parts: the spire and the body
whorl.
The spire represents the posterior part of the shell and may have a
very variable conformation, not only between the different species but inside the same
species too. In few species the spire has a length exceeding the third part of the whole
shell while in most cases it’s not much raised, flat or even slightly concave. The
spire is often characterised by conic tubercles (coronations) which are of great
importance in Conus identification even if very often they are much variable inside the
same species too.
The beginning of the spiral winding of the shell is named apex
or protoconch.
The body whorl contains most of the animal included the foot and the
proboscis. It’s usually coloured with textures and patterns of different types and
may be provided with relieves and sculptures with a spiral or lengthwise
course.
The animal comes out from the shell through a narrow and elongated
opening called aperture or mouth. The free part of the aperture is called outer
lip while the opposite one is called inner lip. The Conus' outer lip is strong
enough in the adult forms but rather fragile in the immature ones. In some species there
is a relief in the medium part of the outer lip. There are not teeth unlike other similar
molluscs. The Conus' aperture is often of a different colour compared to the remaining part
of the shell, in pink or bluish tones, but lacking in coloured patterns.
In the anterior end there is a smooth and shining fold, the
columella, that in Conus is rather short, less than
the third part of the inner lip whole length, and represents the axis round which the shell
wraps itself up.
The outer lip’s upper margin is separated from the shell’s
body by a U-shaped notch, the posterior canal, through which the animal excretes
the wastes. The siphonal canal is situated in the lower margin of the outer
lip.
The anal
canal is of great importance for the classification of the Genus. It is an elongated cut made by the pallium’s margin on the second-last whorl of
the shell. This notch isn’t easily visible from the outside unless breaking the
specimen at the shoulder level. In the anal canal two parts may be
distinguished: the track,
that’s parallel to the shoulder, and the exit that presents a curve in
direction of the shoulder that may change from species to species.
The operculum, made with horny material, has usually an elongated shape
and a brownish colour but it may also present a rounded shape. In some species it may be
absent. The presence of the operculum may be the proof that the shell is picked up
alive.
As the operculums of many species are almost identical they don't allow a reliable
identification of the Conus.
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