Can anyone help?

[fish flipper]

I have had my tank setup for 4 months now. I purchased from Craigslist and was up for 5 months before I got it. I have been noticing these "worms?" for the past 2 moths and they seem to be getting worse. There are so many of them at this point and are getting longer. My lfs can identify them. Can someone please tell me what they are and how to get rid of them.
http://images.tapatalk-cdn.com/15/09/08/8cf66255787a6a65b272f99c86e84825.jpg
http://images.tapatalk-cdn.com/15/09/08/6018bf6646a3f73e465b209814ce9f3f.jpg
http://images.tapatalk-cdn.com/15/09/08/67c51c4c75f1830da39ba87d2df6d2d3.jpg

[alb_56]

http://www.lionfishlair.com/hitchhiker/hitchhiker.shtml

Syllidae polychaete according to this site.

[Sugar Magnolia]

Those look like digitate hydoids to me.

[fish flipper]

Those look like digitate hydoids to me.
Yes! Quick Google image search shows that is exactly what they are. How do I get rid of them? Are they bad?

[Dkuhlmann]

BAD

Read this: http://www.reefcentral.com/forums/showthread.php?t=2437122

[fish flipper]

Doesn't really say how to get rid of them. Any ideas? I only have a 20 gallon display tank so most fish won't work for me.

[Sugar Magnolia]

You can dab a little super glue gel on the area where they are coming out of the rocks, or reef epoxy.

[fish flipper]

There are thousands of them, I can't exactly glue all of them. They are also in the sand.