Two gay penguins at the Berlin Zoo adopted an abandoned egg in July and have been “behaving like model parents” ever since, BBC News reports. The king penguin couple, Skipper and Ping, previously tried to “hatch fish and stones” before caretakers put the egg at one of the penguin’s feet. “[H]e already knew what to do,” zookeeper Norbert Zahmel reportedly told the Berliner Zeitung newspaper. Zoo spokesman Maximilian Jäger also added that the pair have been “taking turns to keep the egg warm” under their respective flaps of belly skin. However, the egg—which was abandoned by the sole female of the species at the zoo—may not be fertilized and might not produce a chick. If Skipper and Ping are lucky, the zoo could welcome its first chick nurtured by a same-sex couple once the egg hatches in September.