The Bullet cluster has been a poster child for the dark side for years. The cluster is shown below (Source: NASA/CXC/M.Weiss - Chandra X-Ray Observatory). The pink areas show the lit matter that can be seen through a telescope, ie: that actually exists. The idea is that the pink 'bullet' on the right has smashed through the pink 'target' on the left and is still moving rightwards.
However, it was very clear to me that this system is spinning. The bullet at least is spinning, as real bullets do, around the axis which is horizontal, and the blue areas look as if they are along that spin axis. This is a clear prediction of quantised inertia, see my flyby anomaly paper (ref 1) in which space probes speed up near to the Earth's spin axis. This is a schematic of the cluster:
They used to ask "Can MoND take a Bullet?" Well, MoND can't, but QI seems to do fine.
McCulloch, M.E., 2008. Modelling the flyby anomalies using a modification of inertia. MNRAS Letters, 389 (1), L57-60