When the ball was bounced to start the annual Easter Monday clash between bitter rivals Geelong and Hawthorn, the centre square contained eight athletes, one umpire, one Sherrin and a rogue pigeon.

As the first quarter rolled on, the courageous rock dove continued to attend centre bounces and was undeterred by the myriad of studded boots that tore up the turf around it.

Although the winged invader was finally shooed to the sidelines, it did get us thinking about the weirdest and wackiest groups, individuals, items and beasts that have crossed the white line in the past.

With the game of Australian Rules Football now over 150-years-old and enjoying sesquicentennial status, we have almost certainly missed some of the game's strangest objects and intruders, so please, let us know your nominations in the comments.

Without further ado, here are the 11 most abnormal field occupants in our game's great history - besides Mark 'Jacko' Jackson.

7. The Black Cat (1923)

The origins of each AFL team's nickname are as varied as they are strange. Some - like the Saints and the Crows - are obvious, but others were formed by pure happenstance.

Prior to the 1923 VFL, Geelong were known as 'The Pivotonians', due to the region acting as the long standing railway and shipping pivot for the wider Melbourne area.

Following a particularly poor start to the aforementioned season that saw the club win just two games in the first eight rounds, Herald newspaper cartoonist Sam Wells suggested that the club adopt the moniker of Black Cats, as their luck could not get any worse.

In a clash following Wells' illustration, a black cat was reported to have found its way onto the playing field alongside the hooped footballers. This feline invasion kick-started a four-game winning streak, a run into that year's Grand Final and the nickname sticking.

The strange occurrence was repeated 91-years later at the Adelaide Oval, when a cat of the same shade took off across the goal face at the hill end.