Multiple choice general knowledge What are fingernails and toenails made of? Calcium, magnesium and associated minerals. Sheets of cartilage. Dead skin cells containing keratin. None of the Above Reveal answer Fill a bubble to check yourself C Correct answer Explanation Fingernails and toenails are made of dead skin cells that have been compressed and filled with keratin protein. They are NOT made of calcium or minerals (a common misconception). This keratin makes nails hard and protective.