How do marine worms reproduce?

Most species of worms have separate male and female sexes that generally fertilize the eggs externally.  A few species of marine worms are hermaphrodites, which means that they possess both male and female characteristics and any one can mate with any other of its species.  There are also a few species of worms, such as the Nemertea, from which the segments can break and grow into mature adults.  Other species of worms reproduce through budding, in which a copy of the parent grows off the parent and breaks off to grow into an adult.