Art yarn has sketchy terminology, I assume because it's such a new thing, with still-experimental techniques. The term "coils" and "beehives" and other similar things are applied to more than one curly sort of structure, so I'm calling this coil plying because, hey, it's making coils while plying two threads together! Woo! I'm really wildly creative at that naming thing.
Lets have a look at our victim.
I can't get any closer-up without the camera going blurry or pixellated on me, sorry. But if you look, you can see how it's made.
It's a two-ply. The white is some of my nine miles of crochet cotton (probably more now, I can't quit buying the stuff). The colored ply is some space-dyed wool that I spun thick-and-thin. The thin parts get plied with the cotton in the usual method. The thick parts become coils; you have to anchor it on either side with the cotton. Check it out.
You start a coil holding the 'anchor' ply (it has to be something strong both because it holds the coil together, and because you really put a lot of stress on it during the spinning process) at a ninety-degree angle to the coil yarn. Let the anchor ply wrap around the coil ply a half dozen times. Then reverse the positions: Hold the anchor ply straight and the coil yarn perpendicular to it. Let the coil, well, coil around the anchor ply. You can see how I sort of roll it on. Then pinch your fingers on the anchor ply, below the coils, and shove them northward toward the orifice, mashing them together (how closely mashed is up to you; I like fairly close because it reduces snagging). After that, do another wrap of the coil yarn with the anchor yarn, to hold the coil where you put it. Then off you go, back to regular plying again.
Did that make sense?
Watch it again, a little more closely.
Again, we can't get closer without it getting blurry, and I couldn't slow it down any further without my fingers locking up on me. You can see why this is good for my dexterity and strength though, can't you?
There you have it. Coil yarn. I think I'm gonna knit a cardigan for fall, for the Goober. I'll knit it about ten sizes too big, and it might fit by then.