Single ply yarn with crochet; this swatch is made with the leftover plying single from an earlier project. It's tightly spun, and was never meant to be used without the untwisting that comes from plying, but I had a few yards left over on the bobbin, and tried it out. The fiber content is merino and silk, and it's worked up with a great texture and beautiful hand.
With a yarn with this amount of twist, you need to crochet right off the bobbin, as it will turn into a tangled snarl in a skein. Not the easiest way to work, but the resulting fabric is fabulous.