Aliens in my tank! slug that slimes???

#1
So I was moving several things around in my tank and saw a weird slug looking thing crawling through a rock I picked up. I put it down to go grab a bucket and when I came back it had moved out of the rock. I only got one photo and its not the greatest in the world. It was a brown slug looking deal, probably 2 inches across and 4-6 inches long. Looked kinda like a ribbon.

I tried to syphon the guy through some water change tubing and he slimed the tubing and got away( I think, the bucket had some gravel and slime, no trace of the bugger). I did have a firefish disappear(probably jumped, still havent found him yet though) and a pair of harlequin shrimp go MIA. Could this guy be the culprit? Do i need to break down my tank and find this guy?

http://i.imgur.com/Q5PRm.jpg

Smack dab in the center of the photo. The majority of him is under the rock.
 
#2
I found out I did syphon him out of the main tank and he is now crawled up in a rock in my 10 gallon qt. Hopefully I didnt kill him in the move, I will try and get him out of the rock and take a better picture.
 
#3
Update: its a polyclad flatworm. I'm curious if more are in the tank and if it ae my Harlequins
 
#5
Yes I have 5 CC starfish in my sump that I cut off legs and fed regularly to the shrimp
 
Top