Leica M Typ 240 Moiré
The Leica M Typ 240 does not have an optical low pass (anti aliasing) filter, ditto for the M9 and M-E. But at 24 megapixels and 18 respectively, the relatively moderate photosite density means that lenses can deliver micro contrast sufficient to generate moiré patterns that can be very difficult to remove.
Here is a moiré example with the Leica M Typ 240 I came across today.