Friend or Foe hitchhiker slug?

I went to use my mag float and found this guy on the under side of it. Not sure if it is good or a pest, it looks like some type of nudi, any help would be appreciated I didn't quarantine it since my gut is saying that it is just a harmless algae scavenger but I'm not sure. It is currently about a 1/2" long

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I did a little research and I think I answered my own question, it appears to be a saccoglossan opistobranch - Elysia obtusa from the Indo Pacific or a Elysia subornata from the Caribbean based on the color on the top flaps. It appears to just be a algae grazer but any additional input would be appreciated

 

I seem to have issues with pictues so Ill try it again.