Tiny, oscillating worms

[Wilhelm]

While adding a new leather coral to my tank and turning off my powerheads to feed my other corals, I found several tiny, (fraction of an inch long) critters that swim straight up to the surface, stay there a few seconds and then float to the lower part of the tank then repeat the process. They propel themselves through a very rapid oscillating, wave-like, movement of their entire bodies. They are too small to photograph. Also, I do have bristle worms of at least several varieties but am not sure if the new critters are babies of one of the bristle worms. What are they?

As always, thanks for your help.

 

[skene]

If they are reddish then it would be bristle worms. I've seen them swim up like that in my tank.

 

[Wilhelm]

They are white. I have 50/50 lighting and they have just a hint of cream-off white.

 

[basiab]

I think they are a stage in the bristleworm life. I used to have them. But my sixline took care of all worms and now I do not see any anymore.