On May 17, 1984, a quarter horse, Kelley, birthed Zebra E.Q. through an embryo transfer, according to the Louisville Zoo in Kentucky.
It was the first successful embryo transfer from an exotic to domestic equine, which scientists hoped could help in upping a declining population.
At first, experts weren’t sure the horse would take to the baby zebra. They also worried the horse’s milk could be poisonous to the zebra.
E.Q. died in 1999 at the Houston Zoo.
Watch the full story in the player above.