It is common knowledge, found even in basic textbooks, that materials cannot be both tough and hard. Diamond, which is solid crystal carbon, is known as the hardest material in nature; however, it is vulnerable to shock and can be easily broken if hit with a hammer at a certain angle. Meanwhile, nature provides us with some materials that compatibly have high hardness and toughness. For example, seashells, bones, and honeycombs are relatively strong and hard. How is this possible?