Experts at St. Louis Zoo are trying to figure out how a 62-year-old ball python laid seven eggs despite not being near a male python for at least two decades.

Mark Wanner, manager of herpetology at the zoo, said it unusual but not rare for ball pythons to reproduce asexually. The snakes also sometimes store sperm for delayed fertilization.

The birth also is unusual because ball pythons usually stop laying eggs long before they reach their 60s, Wanner said.

"She’d definitely be the oldest snake we know of in history," to lay eggs, Wanner said, noting she was the oldest snake ever documented in a zoo.

The python, which has not been given a name, laid the eggs on July 23. Three of the eggs remain in an incubator and two were used for genetic sampling, while offspring from the other two eggs did not survive, the St. Louis Post-Dispatch reported. The eggs that have survived should hatch in about a month.

The genetic sampling will show whether the eggs were reproduced sexually or asexually, called facultative parthenogenesis.

The only other ball python in the zoo’s herpetarium is a 31-year-old male. The snakes are not on public view.

The private owner gave the female to the zoo in 1961. She laid a clutch of eggs in 2009 that didn't survive. Another clutch was born in 1990 but those eggs might have been conceived with the male because, at the time, the snakes were put in buckets together while keepers cleaned their cages.