1. Australian colloquial term for the flies of the family Calliphoridae (known as blow flies in many other English-speaking regions like North America). They commonly have metallic-looking colors in various shades which may resemble the color blue at times from afar.
2. Bluebottle jellyfish: This name refers to several distinct species of siphonophores within the order Rhizophysalia but most notably _Physalia physalis_, a highly visible marine predator often found drifting near the water's surface in warmer climates around the world.