They are Byssal attachments Mike, I got the clams 18 months ago and knew I'd be moving them a time or two, so I wanted to come up with something to minimize trauma to them. The other benefit is that you can move them easily around the tank to play around with different lighting intensities or if you are just rearranging things. It's very easy to do, you just set them up perpendicularly in an oyster shell and put a piece of live rock (or whatever..) on either side of them to hold them upright until they attach. I've got tons of oyster shells if you ever want to try this.
Jason Gregory clued me in on the angel, I asked him if he knew what large angels had the best chance of being reef safe, he didn't hesitate a second when he told me Azfur angels were the best choice. I did a little research as I always do when thinking about adding a fish unfamiliar to me, Jason was right on the money (not that I ever had any doubts), Azfurs are unusual angels in that they tend to be planktonic feeders for the most part and are considered by the experts to be as reef safe as a large angel can be, they are also known to be quite hardy. He pigs out on flake, actually prefers it over the chopped up seafood medley glop I feed daily, he won't touch Nori or Chaeto. The photos don't do him justice, He's a deep dark blue color, not black, with intense metallic overtones on his head, these colors will intensify as he matures...
If I offended I apologize, I tend to escalate whenever I get caught up in banter...
