Putting that shader on a black half cylinder, this is what it looks like.

If you go back to the tubes you can see that this sure does look like the same thing, only with microscopic tubes.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)