Just occasional posting, at most, over the next week (back the 20th (Barcelona)). In the meantime, enjoy this second excerpt from Eric Olson's The Procession of the Mollusks (a novel):

Know your body! Know yourself!

In most humans, this organ consists of an elongated tube that increases in size as it winds in a spiral around a central axis, or colummella. Each turn, or whorl, of the organ is separated from the next by a suture. At the apex there is often a tiny larval growth (“the nuclear whorls”). At the bottom of the organ there is a body whorl, which is the newest whorl and contains most of our soft parts. The spire of the organ consists of all the whorls above the body whorl. The base of the organ is the bottom part of the body whorl. The body whorl ends in an opening, or aperture (vaginal cavity), through which our feet and head can be extended or withdrawn. In many people, the hind parts of the feet (the heels) carry an operculum, a plate that fits into the aperture when the person has withdrawn from others. Humans are usually dextral, or right-handed, with the aperture on the right side, but some people are sinistral, or left-handed, with the aperture on the left side.
The columella is either solid or hollow; if hollow, it sometimes opens at the base in a small depression known as an umbilicus. The margin of the aperture are called the lips; the sides of the lips farthest away from the columella are called the outer lips and the sides near the columella are called the inner lips. At the bottom of the aperture a basal or siphonal canal is sometimes present. It may be an enclosed tube (uncircumsized) or an open groove (circumsized); a person’s siphon (penis) lies within it. There may be a smaller canal or notch at the top of the aperture for a second siphon, which expels water and waste products.
The inner lips of the aperture consist of the wall of the body whorl, or parietal wall, and the columellar area near the siphonal canal. Sometimes the parietal wall and columellar areas are covered with a thick or thin calcareous layer, or callus, which often has spiral ridges or teeth.
In some people the whorls are angled below the suture and there is a flattened area, or shoulder, between the angle and the suture. Or the whorls may be angled or rounded at the periphery, the widest part of the whorl.
Some people are smooth; others have spiral or axial sculpture, or both. Many are covered with a horny layer called periostracum.