Your bones are full of holes like a sponge. But don’t be alarmed—they were designed that way. Why would anyone make a skeleton out of sponges? Well, spongy (cancellous) bone may look soft with all those holes, but there’s nothing squishy about it. A closer look shows that its fibers are precisely placed to bear stress, like girders on a skyscraper. In fact, throughout your life the bone is constantly dismantling and rebuilding those fibers, called trabeculae, to maintain the best configuration for changing loads, such as the shifting stress caused by pregnancy.
This marvelous design provides maximum strength at minimum weight. Architect Gustave Eiffel soaked up some ideas from spongy bone to help him engineer the Eiffel Tower. One hundred twenty-five years later, his tower still stands as a testament to God’s creative genius. Spongy bone, found mostly inside the ends of the long bones, does more than absorb stresses and bear weight. The holes provide space to store marrow, which produces blood cells. And the surfaces of all those trabeculae release calcium and phosphorus to maintain mineral balance in your body fluids. It’s an elegant engineering solution that only the all-wise Designer, not eons of evolution, could create.