Sling Stones

Sling stones are, logically, the common ammunition for a sling.

Description
They are not in any way different from normal stones, and therefore no shops sell them; they can be found in nature in unlimited quantities, and are always re-usable. However, when a great deal of ammunition is needed at once, then using a rock hammer to reduce big boulders into sling stone-sized pieces is the best method.

Trivia

 * Only in  Ultima Underworld,  Ultima Underworld II, and  Martian Dreams it is necessary to get ammunition for the sling the "manual" way; in all other Ultima installments, the ammunition is gathered automatically.