It was once the palace where the Doge and his family lived, the most powerful people in the whole city.

Today no one lives inside it anymore. The seaweed is master of the house now — red seaweed and corals swaying in the dark like tongues of flame. Marco turns on his flashlight, and in a corner he finds the octopus Polifemo, the guardian of the palace, playing cards by himself to pass the time.

Polifemo has so many arms that he can't remember which cards he's holding in each hand, so he can't cheat! "Come on," says Marco. "Let's go over there and play hopscotch too!" And there he is, jumping along with the mermaid, with the fish, with the girls and the boys!