Crochet shell stitch

Dear users, dear authors,
What is a shell stitch and what can you do with it?
Is it only crocheted, or can it also be knitted?

Would anyone else like to add anything?

There are many different shell patterns. They often look quite complicated, but are generally easy to crochet and quick to make. They’re usually created by working a group of double crochets or triple crochets into a single stitch or around a few chain stitches. This creates a loose, flowing drape and is suitable for many garments, blankets, and accessories. Depending on the type of shell pattern, however, the result can also be quite voluminous.
Shell patterns are usually associated with crochet, but they can also be knitted.