Flatworm in the tank -- good guy or bad guy?

[Echale3]

I saw this on the glass, and as best I can tell, it's some type of flatworm. It doesn't seem to be bothering any of our corals, but it doesn't seem to be doing anything beneficial like eating algae.

I reviewed several posts on here, but can't seem to find one where something looking like this is identified. Anybody got any ideas?

 

[KrisReef]

That's one heck of a cool picture. You can clearly see the devils horns on top of its head.

I have a rule that I often break, if I don't recognize the critter I presume it crawled out of the pit of hell to raise havok on the whole tank. Dead critters, once removed from the tank pose almost no threat other than to stink up the trash or clough up the drain pipes. I would give this thing a witch trial and see if it stinks or cloughs, and if it doesn't it was innocent.

Don't mess around with things you don't know

Its too dangerous for most of us.

 

[Echale3]

 

[Echale3]

I finally ID'd it! I was cleaning the front glass and bumped it with the scraper and it fell off. I picked it up, and it has a hard shell. Took a closer look, it turns out it's a slipper snail.

Found a second one in the tank, too.