Indeed pyrosomes use a very interesting form of reproduction. They actually use both sexual and asexual form of reproduction each time they reproduce. Pyrosomes, which are colonial tunicates, produce both egg and sperm. In each pyrosome of a colony, a single egg is fertilized and develops into a 4-staged animal. This form leaves the parent body and starts forming its own colony. It does so using the process called budding, which rapidly develops a new colony of pyrosomes. You can see here, here or here for more information.
