Clarence and Carl Aguirre (born April 21, 2002) are former conjoined twins born in Silay City, Philippines. They were conjoined at the top of the head (vertical craniopagus). In 2003 they were brought to the United States by their mother Arlene in the hope of having them surgically separated. A revolutionary new process was used in separating the twin boys. Because "marathon" surgical operations have historically led to a high rate of mortality and morbidity, Clarence and Carl's doctors chose to separate them in several smaller operations, allowing the twins to recuperate after each surgery.