Magma missiles were Yuuzhan Vong guided missiles, widely used by their capital ships.
A magma missile was a solid projectile with a rocky outward appearance, presumably formed from solidified magma. They were fired from missile launchers known as rock spitters. Like the concussion missiles used by warships of the Imperial Navy and New Republic Defense Force, they were capable of looping flightpaths to attack targets outside of their launcher's direct field of fire.
Magma missiles were thus very different in appearance and performance from the molten slugs fired by plasma cannons, which were unguided, line-of-sight artillery projectiles, the Yuuzhan Vong equivalent of turbolaser bolts. Nonetheless, rock spitters were regularly combined with plasma cannons in mixed weapons batteries aboard Yuuzhan Vong warships.
The existence of a separate Yuuzhan Vong guided missile system is established in The New Jedi Order: Star by Star and The New Jedi Order: Destiny's Way, but the distinction between the plasma cannon and the magma missile has been blurred in other sources. As a result, it is not clear whether the rock spitter should be considered along with the plasma cannon as a variety of Yaret-Kor.
- The Complete Star Wars Encyclopedia