A Petrov type I and generically asymmetric rotating dust family
  The general line element corresponding to the family of algebraically general, gravito-electric, expanding, rotating dust models with one functionally independent zero-order Riemann invariant is constructed. The isometry group is at most one-dimensional but generically trivial. It is shown that the asymmetric solutions with constant ratio of energy density and vorticity amplitude provide first examples of Petrov type I space-times for which the Karlhede classification requires the computation of the third covariant derivative of the Riemann tensor. 
Lode Wylleman