Pikaia

This is a lace sock that can be knit toe up or from the cuff down, with a slip stitch heel. There are 2 sizes, a 72 stitch leg and a 66 stitch leg. There is an option for doing the toe of the toe up sock in an eye of partridge stitch.

Pikaia gracilens
A very primitive fish-like animal. This creature may have been the first true chordate (that is, an animal with a “notochord” running down the length of its back, rather than a backbone). But Pikaia did have a basic body plan that stamped itself on subsequent evolution: a head distinct from its tail, bilateral symmetry (i.e., the left side of its body matched up with the right), and two forward-facing eyes, among other features.

However, not everyone agrees that Pikaia was a chordate rather than an invertebrate; there’s evidence that this creature had tentacles, and some of its other characteristics fit strangely in the vertebrate family tree. Whatever the case, though, Pikaia lay very near the root of vertebrate evolution