Doctors began surgery on a rare parasitic twin Friday in the Dominican Republic. Rebeca Martinez was born with a partially formed second head, called craniopagus parasiticus. The surgeons attempted to remove it because it threatened the seven-week-old girl's survival. The two heads share arteries, but have individual brains. The brain on the parastic head is only partially formed; the head also has ears, eyes and lips. Unfortunately, baby Rebeca died from post-surgical complications on Saturday, February 7, 2004.