A pair of male royal penguins have adopted an egg at the Berlin Zoo after failed attempts to hatch a stone. Aged 10 years old, Skipper and Ping had shown a desire to have an egg in the past and are an "excellent option" according to zookeepers. If the situation is not uncommon in theseanimals, it will be a first in Berlin, which would see the birth of its first baby penguin in more than 20 years.