A dog has given birth to the first identical twin puppies https://t.co/KQswvWOc0k pic.twitter.com/a7L3ACV2nd — BBC Earth (@BBCEarth) August 31, 2016

Kurt de Cramer, a vet working in a suburb of Johannesburg, South Africa, was performing a C-section on an Irish wolfhound when he found something he never had before—two live puppies, attached to one placenta. Identical twins.

Only once before had de Cramer seen two puppies sharing a placenta, he told BBC Earth, and they had died before they were born. These two, though, were alive. He delivered them, along with their five littermates.

Although de Cramer suspected that the puppies were identical, he couldn’t be sure. They had slightly different markings. But DNA samples of their blood and tissue, as well as comparisons to their littermates confirmed what he had suspected: the adorable puppies were identical twins.

It’s rare to find identical twins in species besides our own. Often, the BBC explains, the placenta of other animals cannot support two fetuses on one placenta, so even if identical twins begin to form in the womb, they don’t make it through the full gestation period.

It’s possible that identical twins are more common in dogs than we know, but this is the first confirmed pair ever to be discovered. Their names are Cullen and Romulus, and they’re doing just fine.

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