A varix is an anatomical feature of the shell of certain sea snails, marine gastropod molluscs. Gastropods whose shells have varices are primarily families and species within the taxonomic groups Littorinimorpha and Neogastropoda.
The operculum is a corneous or calcareous anatomical structure like a trapdoor that exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails; the structure is found in some marine and freshwater gastropods, and in a minority of terrestrial gastropods, including the families Helicinidae, Cyclophoridae, Aciculidae, Maizaniidae, Pomatiidae, etc.
The umbilicus of a shell is the axially aligned, hollow cone-shaped space within the whorls of a coiled mollusc shell. The term umbilicus is often used in descriptions of gastropod shells, i.e. it is a feature present on the ventral side of many snail shells, including some species of sea snails, land snails, and freshwater snails.
The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage. Some gastropods appear shell-less (slugs) but may have a remnant within the mantle, or in some cases the shell is reduced such that the body cannot be retracted within it (semi-slug). Some snails also possess an operculum that seals the opening of the shell, known as the aperture, which provides further protection. The study of mollusc shells is known as conchology. The biological study of gastropods, and other molluscs in general, is malacology. Shell morphology terms vary by species group.
The columella or pillar is a central anatomical feature of a coiled snail shell, a gastropod shell. The columella is often only clearly visible as a structure when the shell is broken, sliced in half vertically, or viewed as an X-ray image.
Tegula pulligo, common name the dusky tegula, is a species of medium-sized sea snail with gills and an operculum, a marine gastropod mollusc in the family Tegulidae.
Lauria cylindracea, common name "the common chrysalis snail", is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Lauriidae.
Cittarium pica, common name the West Indian top shell or magpie shell, is a species of large edible sea snail, a marine gastropod mollusk in the family Tegulidae. This species has a large black and white shell.
Tegula excavata, common name the green-based tegula, is a species of sea snail, a marine gastropod mollusk in the family Tegulidae.
Haplocochlias swifti is a species of sea snail, a marine gastropod mollusk in the family Skeneidae.
Gaza superba, common name the superb gaza, is a species of deep sea sea snail, a marine gastropod mollusk in the family Gazidae, the top snails.
Gibbula multicolor, common name the multicoloured topshell, is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.
Ethalia is a genus of sea snails, marine gastropod mollusks in the subfamily Umboniinae of the family Trochidae, the top snails.
Tegula cooksoni is a species of sea snail, a marine gastropod mollusk in the family Tegulidae.
Tegula rugosa, common name the rough top shell, is a species of sea snail, a marine gastropod mollusk in the family Tegulidae.
Bolma guttata, common name the sandpaper bolma, is a species of sea snail, a marine gastropod mollusk in the family Turbinidae, the turban snails.
Ethaliella pulchella is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.
Cirsonella naticoides is a species of very small sea snail, a marine gastropod mollusk or micromollusk in the family Skeneidae.
Eurytrochus maccullochi is a species of small sea snail, a marine gastropod mollusk in the family Trochidae, the top snails.
Ethalia sanguinea is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top-snails.
