Can someone ID this nudi? (pics)

[mathias999us]

I've seen this guy in my tank for a month or so, and today, he went out on the glass for the perfect photo opp:

Is this dangerous? Should I yank him?

TIA,
Mathias

 

[LeslieH]

It appears to be an aeolid nudibranch, the kind that eats corals. Read this for more information: http://www.reefkeeping.com/issues/2005-05/rs/index.php