Yes they are, they both are designed to clean their environment. This specific worm, S. krausii, is a filter feeder and it keeps the water clean by filtering out ('eating') organic and mineral paricles. Without these filter feeding worms, the marine environment will become 'dirty' and other sessile organism can smother to death. The earthworm have a similar task, as you know. Without them the soil won't be fertile or oxygenated for plants to grow in.

My dad is currently working with earthworms, giving them dead soil to enrich again. I also find the earthworms fasinating!