Ilbia mariana in an ascidian

Dear Yuji,
Certainly in colour these animals inside the ascidian wall look like juvenile Ilbia marina but they seem to have thin orange, forked, structures coming out of the front (or back?) of the black section. Did you actually take one of these things out of the ascidian and have a look at it?

Nothing's impossible, but Ilbia is a herbivore, so it is a strange place to find it in large numbers like this. Unless you actually looked at one out of the ascidian, I would be inclined to think this was some sort of parasite, or worm. I look forward to your comments
Best wishes,
Bill Rudman