Compared to the basic shell stitch, which is made with double crochet stitches, this version looks big and bold. It's worked using the treble crochet stitch, so the shells are taller, and they are also wider as well. You probably can't tell just from my photo alone, but if you held a swatch of each fabric side-by-side you'd definitely see the differences.
I've used bold colors to crochet my sample swatch, but you could use any colors in this design. It would be lovely in many different colorways, and also in a solid color.