Duck mussel

The duck mussel (Anodonta anatina) is a species of freshwater mussel in the family Unionidae, the river mussels.

Description
See Animalbase below (external link).

Right and left valve of the same specimen:

Distribution
The native distribution of this species is European-Siberian.
 * Croatia
 * Czech Republic – in Bohemia, in Moravia, least concern (LC)
 * Germany – (Arten der Vorwarnliste) Listed as specially protected species in annex 1 of the Bundesartenschutzverordnung.
 * Great Britain
 * Isle of Man – National Biodiversity Data Centre, Ireland found at Lhen mouth (1922–25) and at Guilcagh (1985). Not protected by Wildlife Act 1990.
 * Ireland – recorded through much of the country
 * Netherlands – yes
 * Russia – Northwest European Russia to Siberia
 * Slovakia
 * Sweden – it is the most widely distributed large freshwater bivalve in Sweden
 * Spain
 * Finland