Gordon they come from the plant crushed to about 2-3" pieces. You spread them with the loader about 4-5" deep then top rake by hand . Some times I roll them but you don't have to as the car traffic does the job also. It took me some time to start as I needed to weed and spray the entire driveway before starting to spread the shells. Now it will go much faster as I can do about 100 feet per night after work in about an hour. They do break down to small chips about 1/8-1/4" and become as hard packed as concrete. It took 10 trailer loads (26 yards ea.) 3 1/2 years ago to put down the first layer at 12".
I get them from a very good friend for the cost of trucking only $50.00 per trip. He sells them for $360 a truck load plus trucking. That works out to about $13.84 per yard and a yard would cover about 100sq' at 4" depth.