A marble is a small spherical toy usually mae from glass, clay, or agate. These balls vary in size. Most commonly, they are about ½ inch (1.25 cm) across, but they may range from less than ¼ inch (0.635 cm) to over 3 inches (7.75 cm), while some art glass marbles for display purposes are over 12 inches (30 cm) wide. Marbles can be used for a class of children's games, and are often collected, both for nostalgia and for their aesthetic colors.