X-shaped (or "winged") radio galaxies exhibit a peculiar X-shape. A widely discussed explanation is the flip of spin caused by the merging of black holes. (https://en.wikipedia.org/wiki/X-shaped_radio_galaxy)

This market resolves to Yes if it is confirmed that black hole spin-flip is the cause of the X-shape for some X-shaped radio galaxy (even if this may not explain all X-shaped radio galaxies).