Dear Bruce,

You are entitled to be puzzled by this/these animals. The tentacles do have the look of a dorid circlet of gills, but they are the feeding tentacles of a Sea Anemone. This is outside my area of expertise but it looks like a genus, Nemanthes, which is often found attached to the stalks of branched colonial animals like gorgonians, sea whips, etc. Because of where it lives, it doesn't have the normal circular attachment base, but instead a long elongate extension out each side to wrap along the stalk it is attached to.

The other interesting thing is the presence of small juveniles alongside, suggesting that this is an anemone that reproduces by budding off small clones of itself. 

Best wishes,
Bill Rudman

Dear Fredy,
I think this is not a nudibranch but rather a Sea Anemone with its feeding tentacles partly retracted. One other animal that came to mind was a benthic ctenophore but I don't think so.

I'm afraid that sometimes it is a bit hard to identify an animal from a single photo, especially when they are not sitting in a 'typical' pose. I don't know of a sea anemone with this colour pattern but I cna't think what else it could be. Perhaps someone will recognise it.
best wishes,
Bill Rudman