Need help ID this slug

[knltn]

I found this slug in my 6 months old tank of mixed corals and fish. Nothing has been introduced lately. What is it? Is it a good guy or bad guy?

 

[Crabs McJones]

Looks like a dendronotid nudibranch, feeds on hydroids

 

[knltn]

I found this slug in my 6 months old tank of mixed corals and fish. Nothing has been introduced lately. What is it? Is it a good guy or bad guy?

Link to the video again,

 

[knltn]

Looks like a dendronotid nudibranch, feeds on hydroids

Thanks for the quick ID. I guess it is a good idea to remove it from the DT. Wonder why I haven’t seen it before and it is so big at almost 3inch long.