Pink sea urchins house five teeth, each supported by a separate jaw in a circular arrangement at the center of their spiked spherical bodies.

But researchers at Northwestern have discovered that the teeth of pink sea urchins are specially equipped to self-sharpen themselves.

The tooth enamel breaks off regularly to sustain precision, like a knife sharpening upon a blade.

“The material on the outer layer of the tooth exhibits a complex behavior of plasticity and damage that regulates ‘controlled’ chipping of the tooth to maintain its sharpness,” said Northwestern University Professor Horacio Espinosa.

The sea urchins continue to grow teeth throughout life, helping the sea urchins ward off predators.