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univalve shell ![click to hear : univalve shell click to hear : univalve shell](../../images/speaker-vert.gif)
Land or aquatic mollusk having a foot and head, which retract into a spiral shell made of a single piece.
morphology of a univalve shell ![click to hear : morphology of a univalve shell click to hear : morphology of a univalve shell](../../images/speaker-vert.gif)
spiral rib ![click to hear : spiral rib click to hear : spiral rib](../../images/speaker-vert.gif)
Protruding line on the whorl of the shell parallel to the suture line.
whorl ![click to hear : whorl click to hear : whorl](../../images/speaker-vert.gif)
Each of the turns around the apex, except the last; its diameter grows.
siphonal canal ![click to hear : siphonal canal click to hear : siphonal canal](../../images/speaker-vert.gif)
Tubular extension of the opening of the last complete turn allowing water to circulate.
inner lip ![click to hear : inner lip click to hear : inner lip](../../images/speaker-vert.gif)
Inner wall of the opening made by the last complete turn of the shell, opposite the outer lip.
columella fold ![click to hear : columella fold click to hear : columella fold](../../images/speaker-vert.gif)
Small protuberance located along the columella.
axial rib ![click to hear : axial rib click to hear : axial rib](../../images/speaker-vert.gif)
Protruding line on the whorl of the shell parallel to the columella.
outer lip ![click to hear : outer lip click to hear : outer lip](../../images/speaker-vert.gif)
Outer wall of the opening made by the last complete turn of the shell, opposite the inner lip.
aperture ![click to hear : aperture click to hear : aperture](../../images/speaker-vert.gif)
Orifice of the last complete turn allowing the head and foot of the mollusk to exit; it also withdraws into its shell through this opening.
suture ![click to hear : suture click to hear : suture](../../images/speaker-vert.gif)
Line marking off the successive whorls of the shell.
columella ![click to hear : columella click to hear : columella](../../images/speaker-vert.gif)
Solid axis of the shell that can be solid or hollow; the whorls turn around it.
nuclear whorl ![click to hear : nuclear whorl click to hear : nuclear whorl](../../images/speaker-vert.gif)
First complete turn of the shell formed at the larval stage.
apex ![click to hear : apex click to hear : apex](../../images/speaker-vert.gif)
Crown from which the shell grows.