Your Inner Fish remains informative and reveals many of life’s secrets. In Chapter 7, Shubin breaks down the composition of cartilage and the main component which makes it so pliant, the proteoglycan complex. He also details the one property common to all animals, which is that an interstitial molecules lie between their cells. Collagen is an important compound, making up over 90% of the body’s protein in weight. It was interesting to discover the patterns of the body plan: cartilage sits between bones to maintain them, and proteoglycans lie between cartilage cells to give them their miraculous properties. One thing remains to puzzle me: what exists in between the bonds of the atoms?