This scallop seashell was crocheted with super fine yarn and a 2.5mm hook, but it can easily be modified to any size. This pattern contains clear instructions on how to adjust the size.

Use as an appliquer, dish cloth, or coaster.
Crochet two, stuff, and sew together to make a scallop plushie.
Crochet two and use them to make a mermaid bra.