Answer: His Heart

Mary Shelley, the English novelist best known for her Gothic fiction and proto-horror genre novel Frankenstein: or, The Modern Prometheus, lost her husband Percy Bysshe Shelley in a tragic boating accident on July 8, 1822.

Percy was cremated but, oddly, his heart didn’t burn with the rest of his body. Historians believe that a bout of tuberculosis in young adulthood led to calcification of the heart tissue which preserved his heart during the crematory process due to the high mineral content. Regardless of the reason behind the mysterious preservation, the heart was retrieved by Percy’s friend Edward Trelawny and given to Mary.

Mary in turn kept the heart, rather than inter the heart with the rest of his ashes, wrapping it in a silken shroud and carrying it with her. The heart traveled with her for the rest of her life—years after her death, it was reunited with her husband, and the rest of the family, when it was put to rest in the family vault in 1889.