Trichuris trichiura 
Trichuris trichiura. Unembryonated 
  egg in feces (unstained, high power). Trichuris trichiura eggs measure 
  50 to 55 µm by 22 to 24 µm. Note the gross features of this unembryonated, 
  fertile egg, ie, the brown, thick, smooth shell with polar prominence (often 
  called polar “plugs”).