Boba balls are soft, jelly-like spheres made primarily of tapioca, which derives from cassava roots. They are the bubbles in bubble tea and are also called tapioca balls, pearls, or boba. In addition to tapioca, they may also contain a sweetener, such as sugar or caramel, along with other ingredients for texture and preservation, like corn starch or potassium sorbate. Boba balls range in size from small (5 mm) to large (8.5 mm); the large pearls are commonly used in bubble tea.