Diphyllobothriasis (fish tapeworm) on stool microscopy Diphyllobothriidae eggs are oval/ellipsoidal and range in size 55-75 x 40-50 µm. There is an operculum at one end and an abopercular (small knob) at the other. Both can be difficult to see. Here is one with an open operculum. Dr. Ahmed Babiker @Ahmed_HBabiker #Diphyllobothriasis #diphyllobothrium #fish #tapeworm #stool #microscopy #clinical #microbiology #operculum