2001 Australian Fifty Cent Coin - ERROR COIN - "ROOZILLA" Single Ridge CUD Error #4
2001 Australian Fifty Cent Error Coin, the "Roozilla" CUD error.
This particular Roozilla features a single ridge.
Due to the location of the CUDs on this coin, the reverse kangaroo appears to have ridges on his back (like Godzilla), hence Roozilla.
A comparative image of said monster has also been provided to better demonstrate these ridges.