Sandwich meat takes many different forms from the more common round shape to sometimes square shape and it's shape depends on how it is made. Most sandwich meat that is round, has this shape because it is stuffed with a stuffer in the same manner as sausage links prior to cooking so it can be consumed in a sandwich. The roundness comes from the casing, which at one time and today in higher quality sausages and sandwich meats are the cleaned small intestines of usually a pig. Square sandwich meat gets it shape for the same reason that bread gets the square shape because they are cooked or gelled in a square bread pan, which is actually rectangular but when sliced appears square. Lunch meat that is made this way usually utilizes a gelatin which must be cooled in order to give it texture and form. So when you are eating a round lunch meat this is due to the stuffing of the meat ingredient into a casing and if it is square it has been cooled into a gelatin state. Turkey breast, roast beef, chicken breast and other lunch meats that are the real item will have the shape of the meat as it is from the animal unless it has been processed or shaped. If you ever go to a deli or meat market and watch as the lunch meat is sliced you will notice that there is a covering around the meat. Bologna is the best example as it is common to see a red casing around the bologna which is the casing used in the stuffing of the ground meat prior to cooking. Since most lunch meat is actually the scrapes from the animal during the butchering process and since waste is an important concept in the processing of an animal nothing is left to waste. The pieces are mixed together and then ground and stuffed or gelled for the lunch meat. This is why real turkey breast, roast beef and related items cost more because it is not the scrapes of the animal which can be a mixture of just about everything from the animal after processing.
