Critter ID, Flatworm?

[orion]

I'd appreciate it if anyone could help me ID this critter and let me know if it’s harmful to corals. They are in my refugium and are very hard to spot. I was lucky enough to get a picture today. I first noticed them about 2 years ago and thought they were flatworms, I used Flatworm Exit 3 times so far but it did not eliminate them.
Thanks,
John

<a href="http://s257.photobucket.com/albums/hh239/jkallaos/Flatworm/?action=view&current=Flatwormb.jpg" target="_blank"><img src="http://i257.photobucket.com/albums/hh239/jkallaos/Flatworm/Flatwormb.jpg" border="0" alt="Photobucket"></a>

<a href="http://s257.photobucket.com/albums/hh239/jkallaos/Flatworm/?action=view&current=Flatworma.jpg" target="_blank"><img src="http://i257.photobucket.com/albums/hh239/jkallaos/Flatworm/Flatworma.jpg" border="0" alt="Photobucket"></a>

 

[rssjsb]

Yep, that's a flatworm. They're not harmful to corals unless they really reach plague proportions.