When he started ranting about how the government was out to get him, I thought he'd 'lost his marbles'. [='gone crazy']
Let's play 'marbles'. = Let's play a game of 'marbles'.
the museum's polished 'marble' floor/staircase
(..) I haven't changed that much, have I? You look like one of those statues you Romans insist on putting everywhere. You look like the clay they make them from. Statues are made of marble, not clay. Not the one they'd make of you. (BOTH LAUGHING) (SIGHING) Look at this. Wow. (..)2016 Ben-Hur