Conch shells hold the secret to impact-resistant armor
 

The conch shell is made of the same material as chalk, but unlike the crumbly rock, it's one of the toughest materials out there. If we can understand why it's so tough, we can mimic it to create nearly unbreakable materials that can be used for safe...

https://www.engadget.com/2017/05/28/...helmets-armor/