The shell stitch makes a row of fans that sit like scallops. It is the classic finishing edge for a shawl, and also makes a beautiful all-over fabric.
The structure
In UK terms the repeat is: skip 2 stitches, 5 tr into the next stitch, skip 2 stitches, 1 dc into the next stitch. In US terms: skip 2, 5 dc in the next stitch, skip 2, 1 sc in the next.
The tall stitches fan out from a single point to form the shell. The short stitch between shells anchors the row and keeps the scallops crisp.
As an edging
Worked as a single round around a finished shawl, the shell stitch gives a soft, scalloped border that adds weight to the edge and helps it hang well.
Things to watch
The repeat usually needs a stitch count that is a multiple of six, plus one. Check the count before you start an edging, and adjust by skipping one stitch fewer or more at the corners.