A 2-year-old Chinese boy "gave birth" to his twin after his stomach swelled to two-thirds its normal size, according to The Mirror.
In his mother's womb, Xiao absorbed his twin who had a fully formed spine, fingers and toes, the article said.
Xiao was rushed to the hospital where his twin brother was removed. If he had stayed, the fetus would have grown into a boy, causing severe breathing difficulties for Xiao, the article said.
The fetus measured 20 cm wide, about the size of a photograph. Better Health said twins form when a fertilized egg splits into two eggs with the same genetic information.
The Mirror said there have been other similar instances in the past. In 2012, the article reports, surgeons in Peru pulled a nine-inch-long parasitic twin that weighed a pound and a half out of a three year old boy.
Also, in 2008, a nine-year-old girl in Greece had a two inch embryo removed, the article said.