Violetastock/Getty Images 

 

Shark teeth are cavity-resistant as they are covered in fluoride. According to a study published in the Journal of Structural Biology, their teeth enamel is made up of fluoroapatite chemical, which makes it less water-soluble and resistant to acid produced by bacteria. The study also found that the teeth of at least two species, mako and tiger sharks, are coated “one hundred percent” in fluoride.