ST. LOUIS (NewsNation Now) — A 62-year-old ball python laid seven eggs despite not being near a male python for at least two decades.

Experts at the Charles H. Hoessle Herpetarium at the St. Louis Zoo are trying unravel the mystery of the unnamed female python who laid eggs July 23.

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

Also making the birth unusual is that ball pythons usually stop laying eggs long before they reach their 60s, said Wanner.

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

Three of the eggs remain in an incubator, two were used for genetic sampling and snakes in the other two eggs did not survive, the St. Louis Post-Dispatch reported. The eggs that survive 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 male that’s about 31. The snakes aren’t on public view.

A 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.