Need help to identify hitchhiker

[ejl2529]

I recently found this (picture below) in my tank. I was wondering if anyone could help me to identify it? Also I am wondering if it is beneficial, bad, or neutral for a mixed reef tank? Thanks for any help.

 

[Tahoe61]

Looks like a nudibranch, no idea what kind though. What have you added to the tank lately in the way of corals or algae?

 

[ejl2529]

Looks like a nudibranch, no idea what kind though. What have you added to the tank lately in the way of corals or algae?

Recent corals have been a long tentacle plate coral, some lobophyllias, a meat coral, some scolymia, and some favia.