Tentacle reaching out from rocks

[rubikcube]

I found this on my rock a while back and never was able to figure out what it is. It hides in the rock most of the time so you can't see it. Here you can see it reaching out of the rock to eat. Any ideas?

 

[Fluff]

Looks like it could be a peanut worm. A rock boring worm that feeds on detrius, harmless tank cleaner.

 

[DragonForce]

I have a few of those guys. They come out at night and don't seem to hurt anything. Adds a nice element of night life!

 

[fishrfreinds]

ive been wondering what those where.