What is this worm?

[Heatherabel3]

What is this?? I found it under one of my rocks in the sand when I pulled it out to tie down some of the Kenya tree branches that broke off. It doesn't appear that it can swim, its just a tube and then the worm thing comes out of it.
http://i1068.photobucket.com/albums/u459/jon_abel1/Mobile%20Uploads/IMG_20150525_191123868_zpskd6n7677.jpg (http://s1068.photobucket.com/user/jon_abel1/media/Mobile%20Uploads/IMG_20150525_191123868_zpskd6n7677.jpg.html)
http://i1068.photobucket.com/albums/u459/jon_abel1/Mobile%20Uploads/IMG_20150525_191108329_zpsywhpc0tm.jpg (http://s1068.photobucket.com/user/jon_abel1/media/Mobile%20Uploads/IMG_20150525_191108329_zpsywhpc0tm.jpg.html)

There were also some eggs under there that I pulled out as well. If this guy is bad and they belong to it I figured better safe than sorry.

[kfisc]

It looks like a peanut worm- not harmful and a helpful addition to your CUC. They live in the rock and extend from it to feed, especially at night. You'll notice that it retracts lightning fast back into the rock when disturbed.