The 10-foot-long, 30 pound mother — named Anna — gave birth to two babies that appear to be genetically identical to their mother, the New England Aquarium said, citing DNA testing. Anna has never been exposed to an adult male snake, the aquarium said.

“DNA testing has confirmed that the 2-foot-long, green anaconda youngsters are the product of nonsexual reproduction,” a release from the Boston aquarium said Thursday. “The extremely rare reproductive strategy is called parthenogenesis, which translated from its Greek word origins means virgin birth.”

Anna also gave birth to a number of stillborn babies, which is common when parthenogenesis does rarely occur among creatures that are not insects or plants, the aquarium said in a release. Three snakes were initially born alive, but one died soon after birth.