What are fire balls used for projectiles by catapults made of?

Fireballs used as projectiles by catapults are typically made of combustible materials designed to ignite upon impact. Commonly, they consist of a mixture of flammable substances, such as oil-soaked cloth or a combination of pitch, resin, and other organic materials. These projectiles are often encased in a container, like a clay or ceramic pot, to help retain the flammable material until it strikes a target and breaks apart, thereby maximizing the incendiary effect.