Marble (toy)

A marble was a small round toy.

A Dogon's sixth eye resembled a blue marble. (TV: Random Shoes)

When the Second Doctor visited Kirith, he had a bag of glass marbles in his pocket. (PROSE: Timewyrm: Apocalypse)

Amy and Rory escaped from a Sontaran ship in 1605 by firing marbles from a slingshot at the Sontarans' probic vents. (GAME: The Gunpowder Plot)