Algae or some kind of worm?

[Sonam]

These appeared on the wall of our 13.5 gallon system. It's been cycled for about 10 days. Initial algae bloom has subsided on the rocks. We have some snails and Hermits in the tank and two firefish. Everyone is doing great.

Just wondered what these were. They seem to have strands of mucus coming off of them. They wave in the current but are attached to the wall.

 

[DSC reef]

Possibly spionid worms

 

[Sonam]

Possibly spionid worms

Thanks. Are they harmful? Or is this part of the cycling of the system?

 

[DSC reef]

There not harmful.

 

[Sonam]

Thank you

 

[Mikedawg]

Might want to read this: http://reefkeeping.com/issues/2003-05/rs/