That's an odd place for a tank, you might say, especially one with such historical significance. Don't fear, it's all part of the plan! The "Mephisto", a German A7V Sturmpanzerwagen dating back to the First World War, is undergoing maintenance at Ipswich before a permanent relocation to the Queensland Museum in Southbank.
Currently located at The Workshops Rail Museum, Mephisto needs a little love and care before it'll be ready for its final home. According to Queensland Museum, along with "corrosion treatments" and "replacing oil and fluids", Mephisto will get a few (non-functional) upgrades in the form of replica guns.
As for the plastic bubble, that's a carcoon and yes, it's "car" and "cocoon" mashed together. The bubble is described as a "de-humidified balloon-like cover" and serves to protect the tank from the harmful effects of, well, air and water.
How did Mephisto find its way to Australia in the first place? I'll let the museum explain:
Mephisto is the only surviving German A7V Sturmpanzerwagen tank in the world, captured during World War One in July 1918 near the French town of Villers-Bretonneux. The tank was salvaged by soldiers from the 26th Battalion, comprised mainly of Queenslanders, who helped recover the abandoned tank and drag it behind allied lines. It was sent to Australia as a war artefact, arriving in Brisbane in June 1919 where it was towed by two Brisbane City Council steamrollers to the Queensland Museum.
So if you find yourself near the Rail Museum, be sure to check it out. Otherwise, you'll have a chance once it's moved to its permanent home in Southbank, sometime in 2018.