When a ball python at the St. Louis Zoo laid several eggs this summer, her caretakers were baffled. The snake hasn't been in contact with a male python in decades, and at 62 years old, she may be the oldest snake to lay eggs on record, AP reports.

The unnamed ball python laid her unexpected clutch of seven eggs on July 23. Two of the eggs were not viable, and an additional two were taken for genetic sampling. The remaining three are being kept in an incubator and are expected to hatch next month.

Genetic analysis should reveal whether the eggs were produced sexually or asexually. Asexual reproduction (called facultative parthenogenesis) is not common in snakes, but it does happen. Sharks, birds, and lizards are the only other vertebrates capable of reproducing this way [PDF].

It's also possible the female snake has been storing sperm and waiting to fertilize her eggs with it. There is one male ball python at the zoo, but he's kept in a separate enclosure. The two snakes haven't had physical contact since the 1990s, so the snake would have been holding on to the sperm for decades.

To make the incident even more remarkable, the female python is much older than most ball pythons are when they reproduce. She arrived at the St. Louis Zoo in 1961 when she was surrendered by her owner. At 62, she's the oldest recorded snake in captivity, and now she's likely one of the oldest ball python mothers ever. Currently, neither she nor the zoo's second ball python are on display to the public.

[h/t AP]