Is this a flatworm?

[namwodahs]

I was just looking at my tank and saw something that looked kinda like coralline algae, but too symmetrical. Is this a flatworm I'm looking at?

<a href="http://www.flickr.com/photos/namwodahs/493030623/" title="Photo Sharing"><img src="http://farm1.static.flickr.com/204/493030623_cbc82e110f.jpg" width="500" height="333" alt="Flatworm?" /></a>

Thanks,
Jason

 

[Opcn]

Does it move? and if so is it a gliding motion or an inchworm like motion? If it glides flatworm is probably the right ID.

 

[namwodahs]

Yeah it moved rather smoothly and quite slowly. I almost didn't even notice its motion at first. This is the first one I've seen so is there anything I should/can do early on to stop them?