File this one under "we think we've just dodged a bullet". Invasive species are a huge problem in general, but even moreso in ecosystems that are isolated. Australia has had all kinds of problems with species that don't have natural predators on the continent in the past (including camels, of all things), and there's even a Simpsons episode that makes a reference to it. Reuters reports that a Giant African Snail was recently found - and destroyed - in a shipping container at the port of Brisbane. Hopefully it was the only specimen on board, but if not, things could get pretty ugly.
Here's how the Smithsonian describes these creatures:
The giant African snail is a true nightmare. These snails grow to the size of a baseball, can lay 1,200 eggs every year, survive all sorts of extreme temperatures, have no natural predators, and eat 500 crops, plus the sides of houses. Also, they carry meningitis that can infect and kill humans. Somewhat understandably, Australia isn’t pleased with any of this.
This is a good reminder of how little it can take for huge damage to be done to ecosystems in our globalized world. They caught this one, but maybe they won't next time, or maybe there are already a bunch of giant snails laying eggs in some corner of Australia, and we'll find out in a few years that they're eating the countryside, houses included.