(CNN) A same-sex penguin couple just became parents at an aquarium in Sydney, Australia.

Sphen and Magic -- or Sphengic, as they are collectively known -- proved themselves natural parents when they incubated a dummy egg given to them by staff at Sydney's Sea Life Aquarium, where they live.

They were then entrusted with a real egg from another couple that laid two during this year's breeding season. Because gentoo penguins usually have only enough resources to raise one egg successfully, the "backup" chick often dies.

Sphen and Magic began developing a strong bond and became inseparable before breeding season, according to staff at the aquarium. Visitors would often spot the pair waddling around and going for swims together, which was why they were deemed to be suitable prospective parents.

The yet-to-be-named sub-Antarctic penguin chick was born on Friday, October 19 weighing just 91 grams (3.2 ounces).

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