Your amazing, versatile, complicated body is tougher than it looks. Between your muscles, skin, cartilage, and bones, your vital organs are surrounded by a structural force field that doubles as an engineering marvel.

So what’s the hardest substance in your body? The answer might surprise you. In fact, the most durable and tough substance in your body is actually a tissue.

Encasing your teeth and helping you chew, bite, and tear your food is your tooth enamel. That’s the hardest substance in the human body.

Keep reading to learn more about enamel and other strong elements in your body.

Enamel is one of four types of tissue that make up your teeth. The other three types are:

  • dentin
  • cementum
  • pulp

Enamel is 96 percent densely packed minerals, which is more mineral than any other tissue your body creates. This makes enamel the perfect protector for your teeth, whether you’re gnashing on jerky or drinking a hot beverage.

Just how hard is enamel?

Studies at the atomic level have revealed that human tooth enamel is incredibly complex. It consists of tightly bunched together, oblong-shaped mineral crystals that are a thousand times smaller than a strand of your hair.

According to the Mohs Hardness Scale, tooth enamel earns a 5. That means it’s about as hard, or harder, than steel. For reference, diamonds are the strongest substance on earth, ranking 10 on the Mohs scale.

Healthline

You might have assumed that bones are the hardest substance in your body. And bones are incredibly tough, also earning a 5 on the Mohs Hardness Scale.

Bones are considered to be stronger than concrete. Fun fact: the jawbone and the femur are considered the strongest bones in your body.

Bone is made of living tissue. Collagen and a mineral called calcium phosphate make up most of your bone structure.

  • Cortical bone tissue is dense, and it makes up the outer layers of your bones.
  • Trabecular bone tissue is the spongy, honeycomb-like material that makes up your inner bones.

The unique composition of your bones is what makes them strong and resilient, but flexible enough to absorb some stress.

Muscles, ligaments, and tendons are also incredibly strong, although they aren’t made up of the hardest materials in your body.

Muscles

Muscles are made of thousands of highly flexible fibers.

Muscles help your bones to move, and also form the walls that surround your organs. Muscles fibers are bound together tightly in groups, which is what gives them their strength.

Ligaments

Ligaments are made of strong, connective collagen tissue.

These bands of tissue are used to hold your joints together and keep your muscles in place throughout different parts of your body. Ligaments are like ropes that keep your muscles from over-extending their reach.

Tendons

Tendons are also made of connective collagen fibers.

Tendons are what connect your muscles to your bones. Tendons are more flexible than ligaments. They also contain fewer blood vessels than your muscles, which makes them more prone to injury.

Muscles, ligaments, and tendons are incredibly strong, and have varying degrees of elasticity. But they aren’t particularly hard, and would rank low on Mohs scale.

Your teeth contain the hardest substance in the human body — your enamel.

Bones aren’t quite as hard as enamel, but they rank closely on the hardness scale.

Other parts of your body (like muscles, ligaments, and tendons) are incredibly strong, but don’t come close to the mineral-based tissue in your teeth and bones.