Apex (mollusc)

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Apex is the, usually pointed, tip of the spire of the shell of a gastropod.

It is the first-formed and therefore the oldest part of the shell. It is the embryonic shell.

The apex of univalves is the top of the shell-tip of the protoconch.

The apex of bivalves is the umbos, beaks or prodissoconch.

The apex of tusk shells is the small, open posterior end.

Like the rest of the shell, the apex is made of calcium carbonate.

The apical whorls, or protoconch, are the whorls at the apex, especially when clearly distinguishable form the later whorls or the body whorl.

The space under the apex of a patellate gastropod is called the apical cavity.