Wiwaxia

Wiwaxia is a genus of soft-bodied animal from the Cambrian Burgess Shale.

Description
Wiwaxia was bilaterally symmetrical. It appeared as a featureless blob with two rows of spines down its "back". Fossils suggest it grew from 2 to 5 centimeters long, but its height remains uncertain.

Discovery
Although fragments of Wiwaxia had been found as early as 1899, Charles Walcott described it fully from the Burgess Shale in 1911 as a type of worm. Its exact classification remains uncertain.