Paleontologists have revealed the fossilized remains of a curious creature that is not only one of Earth's oldest animals, but may even be the first to have ever been mobile. Dubbed Quaestio simpsonorum, the long-extinct species was discovered in the Australian outback by Florida State University geologist professor Scott Evans and his colleagues. Quaestio lived some 555 million years ago in the so-called Ediacaran Period, a key time in the history of life when complex, multicellular life first evolved.

"The animal is a little smaller than the size of your palm and has a question-mark shape in the middle of its body that distinguishes between the left and the right side," Evans said in a statement.

Quaestio is thus the earliest known animal to have a "left-right asymmetry", an important evolutionary development that allowed animals to do different [things] with each side of their bodies, allowing them to adapt to different evolutionary pressures.