Craniopagus Parasiticus or Parasitic Twin
Craniopagus parasiticus is one of the rare and bizarre berth defects or disorders effecting 4 to 6 in every 10 million births. This is an even rarer form of conjoined twins in which twins form when the embryo only partly splits and the twins then remain physically connected. Craniopagus parasiticus is a condition in which a child is born with a parasitic extra head from their unborn/undeveloped or underdeveloped twin. The prime symptoms of this disorder is the presence of an extra head which appears to be more like a parasite.
Craniopagus Parasiticus Cases: On March 2004, an Egyptian baby girl named Manar Maged was born with her twin Islaam attached to her head. The second head (In picture above), Islaam was basically nothing but an incomplete twin (head and upper torso) could smile, blink, cry, and suckle but it could in no way survive on its own. There have only been ten cases of this phenomenon in documented history, with only three surviving birth.