Spriggina.

Spriggina (sprig-EE-nuh) is an odd genus of animal from the Ediacaran Period (about 600 million years ago). No one really knows what kind of animal Spriggina really was--if it was an annelid, arthropod, sea pen, or maybe even something else. Spriggina had a horseshoe-shaped head and many tapering segments that formed a body that looked like a flattened worm.

Spriggina could have had eyes and antennae on the head, but no one really knows if it did have these. On top, Spriggina had overlapping plates of cuticle (cuticle is a hard layer that is not quite a shell), and possibly a mouth in the middle of the head.

Spriggina was probably not an arthropod if it didn't have eyes, antennae, or legs. And also probably not an annelid because it didn't have chaeta, which are bristles.

Spriggina was found in Australia and is 3 cm long.

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