A 13-year-old boa snake who was thought to be male gave birth to 14 babies, even though it hasn't been in contact with other snakes in years, according to researchers at City of Portsmouth College in southern England.

Snakes are capable of parthenogenesis, asexual reproduction that's more commonly known as "virgin births." City of Portsmouth College reptile specialist Pete Quinlan hadn't realized Ronaldo the snake was pregnant, he said in a news release.

"Ronaldo had been looking slightly fatter than usual, like he'd eaten a big meal, but we never thought for a moment that he, or should we say she, was pregnant," Quinlan said.

The baby snakes were discovered by a student during a routine vivarium check. The college described it as a "miracle birth."

"At first we thought she must have been mistaken," said animal care technician Amanda McLeod in a news release. "We couldn't believe our eyes!"

Gestation for Brazilian rainbow boas lasts about five months, according to the National Zoo. There are 12-25 baby snakes in a typical litter. Babies of the species are usually 15-20 inches long, while adults can grow to be up to 6 feet long. Ronaldo is 6 feet long.

It's believed this is only the third time a captive Brazilian rainbow boa snake has had a virgin birth, according to the college. Parthenogenesis also occurs in the wild.

A 2010 study published in Biology Letters documented the case of a boa that gave birth to 22 offspring over two years through parthenogenesis. Another study, published in 2013, documented the case of a 22-year-old captive Brazilian rainbow boa giving birth to four offspring after being housed with a vasectomized male. And in 2019, an anaconda housed at the New England Aquarium gave birth; she was housed with only adult female snakes.

Quinlan, who's been breeding snakes for 50 years, has never experienced this before.

A vet had said Ronaldo was male, according to the college. Quinlan is now working out the sex of the baby snakes and setting up vivariums for them. The newborns will go to new homes once they've grown.