A bizarre creature that looks like nothing alive on Earth today probably used its unique shape to collect drifting particles from the ocean to feed on, researchers from the University of Bristol, in the UK discovered.
Tribrachidium was a denizen of the shallow seas about 550 million years ago. It looked like a disc with three tentaclelike arms protruding from its flat top. Oddly, Tribrachidium had three-fold symmetry, meaning three segments were mirror images of each other. For comparison, humans have two-fold, or bilateral, symmetry, and starfish have five-fold symmetry. Nothing alive today has three-fold symmetry.