Why Are Seashells So Strong?

Materials Scientists at North Dakota State University studied seashells to uncover how they get their amazing strength.

Abalone type seashells have two layers; a brittle outer layer and a tough inner layer made of nacre (mother of pearl). Considering that this nacre layer is composed of around 95% chalk and 5% proteins, the question is; how can it be so strong?

The studies show that the mother of pearl is arranged in a brickwork structure and this makes it both strong and tough. The “glue” that that binds the chalk “bricks” together is actually a mixture of over 30 different proteins. Even though the chalk is normally brittle, the bricklike arrangement and these proteins as “mortar” give them unusal strength and toughness.

When it comes to materials science, strength and toughness are actually two very different things. Strength measures the resistance to impact without breaking. Toughness measures the ability to take an impact without any cracks in the material.

Mother Nature used some of the weakest materials to form seashells, but combined them in such a way to give them amazing strength and toughness.