In crochet, a group of 3 or more stitches (usually double crochet) in the same stitch or space is often called a Shell. When multiple stitches go into the same spot, it looks like a seashell -- at least I assume that's where the name comes from!
The effect is often a pretty texture. However, the more stitches that make up the shell, the more distorted the stitch or space you're crocheting into can become. Depending on the design, the distortion can take away from the overall look and symmetry of the item.
When this happens, there is a technique you can use to avoid putting all the stitches into the same spot. It's called a Foundation Shell Stitch. Similar to a Foundation stitch, you create an extra chain loop at the beginning of the stitch, and then crochet the shell into that loop instead.
Watch the video to learn how to crochet the Foundation Shell Stitch. Find a written pattern for this stitch in the related blog post here: https://www.changepathcrochet.com/avo....