World's Oldest Animal with a Skeleton

Up until recently it has been generally accepted that animals with skeletons did not appear on earth until the Cambrian period, which began approximately 542 million years ago. However, researchers have recently discovered fossilized remains of creatures in Australia that challenge that notion.

The impression in this sandstone bed in southern Australia is that of Coronacollina acula, an animal that lived between 550 and 560 million years ago on what was once a shallow seafloor. The animal looked roughly like a thimble and had four needlelike arms to support its body, each up to 14.5 inches long.

It is likely that Coronacollina acula was a stationary animal that fed by filtering nutrients from the seawater, much like a modern sponge. If the research holds true, Coronacollina acula represents the earliest known animal with a hard skeleton.

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Via MSNBC.