species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is es ...
in the
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
Skeneidae
The Skeneidae are a speciose family of minute to small marine gastropod molluscs in the superfamily Trochoidea.Bouchet, P.; Gofas, S. (2013). Skeneidae. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia. ...
.
Description
The length of the shell varies between 1.2 mm and 4 mm. The smooth, shining shell is narrowly umbilicated. It contains 4½ tumid
whorl
A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs).
Whorls in nature
File:Photograph and axial plane flo ...
s with a deep suture. These whorls are rapidly increasing in size. The base of the shell shows an oblique, arcuate stripe running into the
umbilicus
Umbilicus may refer to:
*The navel or belly button
*Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy
* ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants
*Umbilicus urbis Romae
The ...
This species occurs in European waters, and the Atlantic Boreal to Arctic region. It also has been found as a fossil in the Italian
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Iberus : revista de la Sociedad Española de Malacología v.9 (1990) * Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca, in: Costello, M.J. et al. (Ed.) (2001). ''European register of marine species: a check-list of the marine species in Europe and a bibliography of guides to their identification''. Collection Patrimoines Naturels, 50: pp. 180–213