Very pretty to look at, but.... Initially crushed shells can smell very fishy, but this fades over time. The biggest problem is that shells can get stuck in shoes with deep treads on the sole and then as you walk around your house the shells will scratch your floors.

Most of my rural family had those, it was just a practical thing growing up on the Gulf coast. But really nasty for skinning your knee when learning to ride a bike.

Crushed shell, normally oyster shell, is a great material to use if you are in a coastal area and it is readily available. Yes, it has it's less favorable attributes as describe above. If you want to use an alternate material with a similar appearance, consider using a quarter minus gravel. Every stone and gravel supplier uses a different name for this material. You want a gravel that is graded were the pieces range in size from 1/4" down to dust. It packs well and wears well; however, you must have the proper base material underneath it for it wear and pack properly.