What is this?

[Cord]

Can anyone help me identify these strands growing out of my substrate.  They are normally not visible, as they hide just beneath the surface of the sand, but I recently increased the flow which has caused the sand to be slightly displaced and reveal these.  Good? Bad? normal?

[Rosco's Reefs]

probably sea-fans... ever see any sort of little feathery protusions?  These are normal and desired, just filter feeders

[Cord]

like feather dusters? if so I have small ones all over my live rocks

[sachabballi reef]

good...filter feeding feather duster type worms..cant think of their name right now

[Squishie89]

I have those. I never see anything come out. I call them sand worms. If you look through the sand more you will find more.
http://www.reef2reef.com/forums/reef-aquarium-discussion/133621-infestation-sand-tube-worms.html

[Cord]

Thx folks. Good to know it is not anything that will lead to a disaster.  I have had too many disasters