All cattle have fat between their muscles. This is a normal part of their growth. If a steak contains more than one muscle, you can see a line of fat between them. However, this should not be a large chunk of fat, just a small line. This seam fat is a big problem, because the meat cutters in the store cannot cut it off the steak as they can with fat on the outside. Seam fat is another kind of waste fat. Choose steaks that have very little seam fat.