It sounds like a joke, but cotton candy—one of the most iconic sugary snacks—was invented by a dentist. In 1897, Dr. William Morrison of Nashville teamed up with confectioner John C. Wharton to create a machine that melted sugar and spun it into fine threads. They called their invention Fairy Floss.

The sweet treat made its debut at the 1904 St. Louis World’s Fair, where it was a smash hit—selling over 68,000 boxes at 25 cents each.

By the 1920s, it was a carnival staple. And in 1921, another dentist, Joseph Lascaux, improved the machine and renamed it cotton candy—the name that stuck.