Bimonster

The wreathed product of the monster group by . The bimonster is a quotient of the Coxeter group with the above Coxeter-Dynkin diagram. This had been conjectured by Conway, but was proven around 1990 by Ivanov and Norton. If the parameters in Coxeter's notation are written side by side, the bimonster can be denoted by the beast number 666.