Marginellidae

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Marginellidae, or the margin shells, are a family of small, often colorful sea snails. They are marine gastropods in the clade Neogastropoda and belong to the superfamily Volutoidea. Most species live in the ocean, with only two known freshwater species.

Classification has long been confusing. Many books grouped all Marginellidae in a single genus, Marginella, based on shell appearance. Early classifications relied on shell features that can be misleading. Detailed study of living animals’ soft parts and more recent molecular data have clarified their relationships. In 2019, a molecular study by Fedosov and colleagues reshaped marginelliform gastropod taxonomy.

Shells are usually small. Colors range from white and cream to yellow, orange, red, or brown, and may be solid or patterned. The protoconch (the first shell) has few whorls. The outer lip is thickened and may be smooth or have tiny teeth. Some species have an external varix; some do not. A siphonal notch may be present or absent. The columella (inner shell folds) typically has 2–6 plications. The operculum (the little trapdoor) is absent.

Within Marginellidae, the subfamily placement is uncertain (Incertae sedis).