Assulina muscorum, 54 µm, stacked image
Genus Assulina Greef, 1888
Diagnosis: Shell usually brown, ovoid, compressed, biconvex in cross-section, with overlapping elliptical scales; aperture narrow oval, more or less crenulate with organic margin; nucleus vesicular, filopodia.
Assulina – after Lüftenegger et al, 1988