there's a variation of coral stem called "CoralStemWithNeurons" which as the name implies is a bundle of coral neurons attached to a single coral stem to me this implies the coral neurons (red) grow out of coral stems (the segmented axon looking one) to later detach and reallocate to where it's needed
I've known about this for a while and I've been meaning to make a post on it but i've not had time to draw the diagrams i want to draw for it; so here's a quick post with screenshots so I can reference it later