The PLoS One community blog writes, about some of the famously curious Burgess Shale fossils:
A number of the strangest fossils from the Shale are so difficult to classify using current animal classification, they were given designation Problematica until more information is uncovered. One such new fossil that helps move some members of Problematica into a more specific group, was recently discovered. This fossil, Herpetogaster collinsi , was described last week in PLoS ONE by Jean-Bernard Caron of the Royal Ontario Museum, Simon Conway Morris from University of Cambridge and Degan Shu from the Northwest University in China in the article Tentaculate Fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) Interpreted as Primitive Deuterostomes…
(Thanks to investigator Ellen Grimes for bringing this to our attention.)