Good or Bad Nudibranch

I have what i believe to be nudibranches. Its a clear smooth bodied slug like creature. a pattern of white kinda like a horse shoe on its back but not raised. Gills and anus is clearly near the head. one on either side. Head is extended like that of an elbow noodle pointed down. When i feed the fish it releases very long tentacles that are exceptionally thin. When they contact fish or food they retract quickly and disappear into the body then are quickly re-released. Contacting a coral they do nothing. The shape of the tentacles is:
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Is this a pest that i need to get rid of?

 

sea apple?

 

Stomatella snail? They have a snail mouth (downward elbow noodle) and often have hairlike "tentacles" off their sides. If so, they're good guys.

 

Yep thats them. Thank you.
+1

 

Never would've got that from that description LOL.