For the whole gorgonian see here: http://www.inaturalist.org/observations/4841850 In this somewhat closer photo there is a bump on the stem to the right of center in this photo. The bump shows a little dark opening and inside that is one individual of the Seawhip Barnacle which has been partially overgrown by the tissues of the gorgonian. The Seawhip Barnacle is an obligate commensal. I should actually have taken a close-up, and more of them, as there were a few of them dotted here and there on this big sea plume. But the gorgonian was extremely stinky by this point, and it was cold in the backyard, and I was tired. Plus I could not remember exactly what these were at the time. I found this big gorgonian washed up at the last possible moment before leaving Sanibel, so I stuck the whole thing into a big plastic bag in my suitcase so I could deal with it when I got home to NYC. I suspect that the little round knob at the end of one of the side branches slightly to the left of the main barnacle might actually be another much smaller one, one where the barnacle died and was completely overgrown by the sea whip tissue.