Surface-to-air rocks, also known as surface-to-surface rocks when used alternatively, are projectiles used as the primary weapons of the Royal Earthbender Guards. Usually launched from the watchtowers outside of the Earth Kingdom Royal Palace, these large earthen frusta are used both as offensive and defensive armaments. Once possible threats to the earth monarch's safety are spotted, several of these rocks are lined up and fired in quick succession so as to effectively prevent invaders from bypassing the palace's defenses.