100 Pcs Bulk Cut Sea Shell Beads Cowrie Craft

Do these shells look like the ones in the picture? They must be "opened" in the back for my purpose.

Average dimensions of the shells or are they variety sizes? I’ve started a piece but I need them to match the ones I already have

Do these come with an odor or are they clean?

How big are these shells? I need quite small ones. I know they'll vary, just looking for an average or range.