Good or bad nudibranch?

[BAMslam93]

Hi all,

I recently came back from my LFS to pick up some corals and I thought I got lucky enough to get a berghia nudibranch hitchhiker on my acan but I'm not sure if it's a good nudi or a bad one like a zoa or montipora eating nudibranch.

 

[Tahoe61]

Well I would isolate it until you get an ID.