Koopa Troopa

Koopa Troopas (usually Koopas, Japanese ノコノコ Nokonoko, sometimes called Turtles) are common enemies in the Mario series, usually displayed as foot soldiers of the Koopa Troop, under the direct leadership of Bowser. Koopa Troopas are turtle-like creatures with removable shells that come in many different colors, with red and green Koopa Troopas being the most common.

Goin' Green
A green Koopa Troopa eliminated the Rat King in the opening round, and Godzilla in the second.