A wombat
The other day I mentioned that I did not get to see a wombat. A parishioner from home sent me a picture of one. It is the L6 Wombat (Weapon Of Magnesium, Battalion, Anti-Tank), a 120 mm calibre recoilless anti-tank rifle used by the British Army before the invention of guided anti-tank missiles, though it was retained until the late 1980's for possible shoot and scoot attacks in built-up areas in case of attack by the Warsaw Pact.
I can't think why the Healsville Wildlife Sanctuary would need a collection of these. Perhaps there are occasional riots by psychotic emus or something.