small worm growing into a big worm how can you tell it was the same worms? Maybe what you saw was a Dorvilleidae, but you also had Eunice worms. Having one doesn't exclude you from having both.
I will repeat myself, it is the band behind the head. While I was mistaken on my worms. What became very clear was the mark behind the heads. What I once thought was a dorville worm, I started to question as I watched them roam the glass and one night, no longer to be seen. I should have taken pictures. I regret not doing so.
When I did my tear down to upgrade the aquarium. I found the worms I saw once again. They were in the sand. 5 of them
How do I know they were the same worm? The mouth .. the jaw. That weird white head band, it was not transparent. The way they grabbed their food. They roamed the glass and sand, picking up algae and left overs. They had weird jaws. Like "The Predator" almost, if you would call it that.
I needed to know what this worm was.
I looked and looked and ran into eunicid species.
And now the event above, there was one eunice left I did not notice was living in my live rock. Until I saw it go after my skunk shrimp.
If I had taken pictures from the start to this point, you would have your answer how I know what my worms are.
Now for the OP... Only he can truly tell us if there was a white band or not. Or if it looks like the worm above. If It was in more apperance of the dorville. My appologise to the worm. I got it killed.