Musculium lacustre

Musculium lacustre, the Lake Fingernailclam, is species of small freshwater clam, an aquatic bivalve mollusc in the family Sphaeriidae, the fingernail clams and pea clams.

Description
The 8–11 mm. shell is oval to quadrangular in shape. The umbos which are capped by the juvenile shell are slightly in front of middle directed forwards. The posterior end is broad and truncated. The shell is fragile, fairly glossy and pearl grey to white in colour. The periostracum (surface) is ornamented with fine, even, concentric striation.

Distribution
The native distribution of this species is Holarctic and occurs in islands and countries including:
 * Algeria
 * Belgium
 * Czech Republic – in Bohemia, in Moravia, near threatened (NT)
 * Slovakia
 * Germany – (Arten der Vorwarnliste)
 * Great Britain
 * Ireland
 * Nordic countries: Denmark, Finland, Sweden (but not in Faroes nor in Iceland)