The Clam Worm is also known as Nereis succinea. Clam Worms reproduce sexually and fertilization occurs externally. When sexual maturity is reached, individuals metamorphose into a nektonic heteronereid form similar in appearance to the non-reproductive form except the parapodia have become enlarged and more lobate. While spawning the worms swim to the surface to spawn in mass. The males and females release their gametes and the females' eggs become fertilized. The eggs eventually hatch and a young Clam Worm is created.
This picture shows how the clam worm is very similar but different in size from when it is young compared to when it is an adult.