Pisidium milium is a species of very small freshwater bivalve in the family Sphaeriidae, the fingernail clams and pea clams.
The 3.0- to 4.5-mm shell is tumid (swollen). It is more rectangular than other Pisidium species and has broad, swollen umbos which lie behind the midpoint. The surface (periostracum) is very glossy, with irregular, concentric striae. The colour is yellow to pale brown.
The native distribution of this species is Holarctic.
