What are those crunchy white parts in spare ribs?
Mammalian ribs are not entirely made of bone. At the end where they abut on the sternum (the anterior end) beginning with the about the 7th or 8th rib down to the 12th
rib (the last one, next to the abdomen) there is a section of cartilage. The cartilage tip
sections of the ribs fuse together producing a smooth edge to the rib margins below the lower end of the sternum. You can feel this rim of cartilage below your own sternum
where the ribs curve back from the midline.