A symbiotogram is a word or figure that changes into a different word or figure when inverted. The earliest symbiotogram published may be by Peter Newell, in 1893. The first use of a symbiotogram in magic literature seems to be “O' Nertz” by Thomas Ruckhill in The Linking Ring, Vol. 14 No. 10, Dec. 1934, p. 844. In this gag, five five-digit numbers are added with some difficulty, and when turned upside down, the total reads “O' Nertz”.