Shell stitch

A shell stitch (or fan stitch) is a crochet motif often used as a border around other patterns or in staggered rows to create a distinctive fabric pattern.

[1] Shell stitches are often used as edging for crocheted items such as Afghan blankets and sweaters.

[1] Shell stitch borders can be worked around any regular pattern.

[3] The visual effect of a shell stitch border may be enhanced by working a single or half double crochet in a contrasting color into the base row and over the shells.

When the entire fabric consists of shell stitches the visual effect may be enhanced by alternating two or three different colors; one for each row.

A cell phone cover made from shell stitch crochet in two colors
A pet blanket constructed from a single granny square with a shell stitch border, enhanced in a contrasting color with half double crochet
Schematic of solid shell stitch, in international symbols. The chain stitches at the bottom are shown only for scale, and are not repeated in the main fabric.
The outer half of this doily was done in a fan stitch.
Schematic of a crochet fan stitch, in international symbols