Spadix (zoology)
In the field of zoology, a spadix ( ; plural spadices , ) is a secondary sexual organ found in some cephalopods and hydrozoans. In the genus "Nautilus", the spadix is a composite erectile organ in the male located in the oral region which is composed of four highly modified tentacles and which is paired with a somewhat smaller antispadix that is also composed of four tentacles. The spadix is normally a concealed organ but quickly becomes distended upon the animal's death. The exact function of the spadix and antispadix in "Nautilus" is not yet known.