What did catapults throw?

Answer 1

Rocks,carved stone balls, iron arrows,lead shot, baskets of venomous snakes, diseased horse carcasses, clay pots filled with asphyxiating gas, flaming barrels of gooey and syrupy chemicals, hornet's nests, dead bodies of captured enemy soldiers, severed heads of messengers, and cow manure. I learned that all in the book The Art of the Catapult.

Answer 2

Historically, catapults were mainly used to throw large rocks. They can throw lots of other things, too.