When zookeepers realized that Roy and Silo were both male, it occurred to them to give them the second egg of a mixed-sex penguin couple, a couple which had previously been unable to successfully hatch two eggs at once.
It occurred to them. This was to give them the second egg of a mixed-sex penguin couple. Roy and Silo were both male. Zookeepers realized this. Sex penguin couple was a couple. This couple had previously been unable to successfully hatch two eggs at once.