This can be a very confusing crochet technique. It took me a while to figure it out. The squiggles are made on a crocheted open mesh. I have seen this technique (by my grandmother) used to make rugs, hot mats, place mats, pillows, etc.
This past week I discovered a neat new crochet method called Wiggly Crochet. It started with this post of a crocheted thrift store hot-pads by Nancy over at Joy For Grace.