Natural light photo. Subject is the female slightly above and to L of centre.
This species seems to be a relatively recent arrival at this and similar GSV dive sites but I am far from certain about that.
Another example from the same dive as my preceding observation. Image 2 may be the appearance in natural light.
Image as for previous submission but subject now the complex fixed colonial animals coating the mauvemouth ascidians.
Because I can't be sure that they are both one taxon I nominate the light brown to grey colony at lower aspect as SUBJECT For ID.
Soft, sponge like to touch