The Engineering of a Shell

HAVE you ever noticed how easy it is to snap a piece of chalk crayon in two? But now, try to snap the shell of the red abalone in two. Chances are you would need a hammer to break it. Yet the abalone shell is made of the same stuff as the chalk​—calcium carbonate. The shell is just put together differently. So differently, in fact, that it is some 40 times more resistant to fracturing than chalk crayon is.

How does the abalone manage this engineering feat? Scientists at the University of Washington in Seattle, U.S.A., have unlocked some of this marine snail’s secrets. The abalone uses its single dishlike shell as a protective wall against the world outside. For the sake of strength, the shell grows in layers. The outer layer is rough and coarse. But the inner layer, called the nacre, glistens in translucent beauty, and herein lies the shell’s strength.

The Washington scientists have learned that this inner layer “has a laminated, brick-and-mortar structure,” notes Science News. Only about a micron wide (one millionth of a meter), these tiny bricks are held together with a mortar made by the abalone itself, a powerful adhesive that scientists are still trying to figure out. Scientists say that the layers of microscopic “bricks” absorb impacts by sliding against adjacent layers. Meanwhile, the organic layers of mortar somehow bridge developing cracks with special “ligaments.” In all, the shell may have as many as five mechanisms for resisting breakage!

Scientists are so impressed with the abalone’s remarkably strong shell that they are trying to develop similar techniques in making strong ceramics. If they succeed, they will no doubt be showered with applause. How sad that the Great Designer, whose work they are striving to imitate, is so rarely given the credit for his incomparable ingenuity!​—Job 37:14.