When trying to find out what had happened to the great dam, the blackboard at Marvin's school and the steel girder on the skyscraper, Batman presented before the Superfriends a riddle: "What do all these materials have in common?" The answer Robin came up with is that they all come from the Earth, in copper mines, slate quarries and so forth.
- ↑ As seen in The Challenge of the Superfriends.
- ↑ As seen in multiple episodes.
- ↑ As seen in The Ultra Beam.