D. pyriformis Ehrenberg, 1838: 45-50 μm long for small varieties, 100-600 μm long for large varieties; 25-30 μm wide (test diam.), small; 70-350 μm wide, large; test flask-shaped, base round or polygonal, narrow tapered neck; chitinoid, large imbedded quartz grains; Symbiont, green alga (Kudo, 1966).