On a lava rock charbroiler, a bed of ceramic "lava" stones are placed above the burners. They heat up and radiate the heat upward toward what you're grilling. Because the rock is porous, it catches and holds drippings, which enhances the delicious smells by creating more flavorful smoke and flare-ups. This added level of flame and smoke looks great in display cooking applications, and some chefs prefer this style because they believe it adds more flavor to the food.