(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).
The aquarium announced the birth on Twitter, saying: "Born Friday 19th October @ 5:46pm, weighing just 91g! Gender TBC in 2 months. Both dads are doing well and are so in love with their precious bub."
Although males are generally heavier than females, the sexes closely resemble one another and therefore experts often need to observe penguins' behavior over a period of time to determine their gender.
Tish Hannan, penguin department supervisor at the aquarium, said on the attraction's website: "Baby Sphengic has already stolen our hearts! We love watching the proud parents doting and taking turns caring for their baby chick."
The two fathers will be responsible for feeding the baby up to 10 times a day over the next five to six weeks. Once it is big enough, it will start to lose its baby fluff, start growing its adult feathers and begin swimming lessons.
Hannan added: "With that said, the first 20 days of a penguin chick's life are the most vulnerable so it is extra important the chick is very happy, healthy and well fed by his parents."
Unusual as their situation is, Sphen and Magic are not the first same-sex penguins to welcome a new addition.
Written by Justin Richardson and Peter Parnell, "And Tango Makes Three" is a children's book based on the true story of Roy and Silo, two male penguins at New York's Central Park Zoo who reared their own chick.