Iodamoeba buetschlii cysts are round to oval and measure 5 to 20 micrometers in greatest dimension. On permanent-stained preparations (e.g. trichrome), the nucleus has a large "blot-like" karyosome, and achromatic granules may be present around the karyosome. Cysts characteristically have a large compact glycogen-containing vacuole which appears as a well-defined, empty-appearing mass on permanent stains.