Half-a-billion-year-old 'marine Roomba' is earliest known asymmetrical animal

An illustration of a shallow pool with a flat, purple, pancake-shaped animal. A protruding backward question-mark shape can be seen on its back. .

The earliest known animal to show evidence of an asymmetrical body lived over half a billion years ago in what is now the Australian outback, a new study reports.

The 555 million-year-old creature, dubbed Quaestio simpsonorum in a study published Sept. 3 in the journal Evolution and Development, was able to move around on the ocean floor like a "small marine Roomba vacuum," eating microscopic algae and bacteria. But this seemingly simple animal hid an exciting discovery: the unique "backward question mark"-shaped protrusion on its back is the first recorded example of an asymmetrical body pattern, a vital step in the evolution of complex life.