What type of rock propelled in catapults?

Answer 1

A catapult is a device used to throw or hurl a projectile a great distance without the aid of explosive devices-particularly various types of ancient and medieval siege engines.[1] Although the catapult has been used since ancient times, it has proven to be one of the most effective mechanisms during warfare. The word 'catapult' comes from the Latin 'catapulta', which in turn comes from the Greek καταπέλτης (katapeltēs), itself from (kata), "downwards"[2] + πάλλω (pallō), "to toss, to hurl".[3][4] Catapults were invented by the ancient Greeks.[5][6]

Answer 2

Strictly speaking, all three could be applicable. Could you be a little more specific with your question?