Pisidium conventus, the arctic-alpine pea clam, is a species of freshwater bivalve from the family Sphaeriidae.
The small (2.2–2.8 mm.) shell is oval in shape and thin and fragile. It is broad and flattened (laterally compressed) with flattened umbos near the midpoint. The colour is yellowish-white and the periostracum (surface) is silky with fine, concentric striation.
P. conventus is a relict of colder climatic periods found only in deep, cold, upland lakes.
