In Chapter 2 of Ian Stewart's Another Fine Math You've Got Me Into... (New York: W. H. Freeman & Co., 1992), he mentions a conjecture that "polyominoes of order 3 do not exist" (a polyomino is "a plane figure formed by joining a set of equal-sized squares edge to edge so that the corners match" and the order of a polyomino is "the smallest number of copies that will fit together to fill a rectangle.")
He tells a story involving a certain worm called Albert Wormstein, then claims that Albert has found a proof of the above statement. He continues:
Albert's proof is too complicated to give here. Interestingly, it makes extensive use of symmetry arguments. Albert is currently publishing it as a joint paper with me, since mathematics journals tend to be reluctant to accept contributions from worms---an appalling example of how science is infested by speciesism. (How many articles by worms have you seen in mathematics journals?) This is the first conjecture in mathematics to have been proved by a worm.
I thought it was some private joke until I discovered this paper: "Polyominoes of order 3 do not exist" by I. N. Stewart and A. Wormstein, Journal of Combinatorial Theory, Series A, Volume 61, Issue 1, September 1992, Pages 130–136.
My question is: Does anyone know why Ian Stewart chose to have a fictional (I assume) co-author? Or is Albert Wormstein a real person?