In mathematics, "moonshine" refers to a set of notorious coincidences connecting quantities from the representation theory of "sporadic" finite groups, and quantities from certain special complex functions. Best known is the moonshine connected with the "Monster group", but recently there has also been moonshine for the much smaller Mathieu group M24, and now there has been further arcane progress regarding this Mathieu moonshine, as reported in Terry Gannon's "Much ado about Mathieu". This is all another link in the chain connecting exceptional mathematical objects (like the group E8) with physical "theories of everything". String theory is being used to explain moonshine, which in turn suggests that the fundamental definition of string theory may have something to do with exceptional symmetries. The Monster group gets all the press as the most exceptional of the exceptionals, because it's the biggest, but according to Gannon's introduction it's M24 that is the "most remarkable" - in the opinion of John Conway, one of the great contemporary mathematicians - because of its centrality in the web of relations connecting the exceptionals. M24 also has natural connections to symmetries in 24 dimensions, the number of dimensions perpendicular to the worldsheet of the bosonic string (which contains 1 space and 1 time dimension, bringing us to the well-known 26 dimensions). I am rather inclined to think that the superstring is just a sector of the bosonic string, and so it's easy to suppose that "Mathieu moonshine" corresponds to something universal in string theory, perhaps related to the universal AdS3 factor of spatial geometry near a string.