Emergency..What is this slug?

[j_g]

He just appeared one day out of the blue. Is he harmful to my reef tank. I only have a 20 Gallon reef tank and this guy is 4 inches long.

 

[j_g]

ANY IDEAS?

 

[007]

IDK, but put it into a separate container until you find out . . .

 

[j_g]

STILL ANY IDEAS ON WHAT THIS IS?

 

[cprdnick]

I would search here, after about 4 hours of searching I found mine.
http://www.seaslugforum.net/species.htm