The Scaphella junonia johnstoneae, or Johnstone's Junonia, is an offshore seashell common to the Gulf Coast. The shell was described by a Harvard scientist, Dr. William J. Clench. He named it in honor of Kathleen Yerger Johnstone, an amateur conchologist from Mobile, Alabama, who popularized seashells through speeches and books.

The Scaphella junonia johnstoneae was made the state shell in 1990 by Act no.90-567.