If you could tiptoe through the Middle Cambrian Burgess Shale in the Canadian Rockies 500 million years ago, you'd come across a tulip-shaped sea creature that defies classification. The 20-centimeter-long animal, given the name Siphusauctum gregarium (Latin for "cup-shaped, gregarious herd member"), was first discovered in 1983. A detailed description was not attempted until now, however, until a Canadian graduate student took interest in it. Siphusauctum's unusual shape and structure has no direct counterparts with any other organisms (fossil, left; artist's impression, right). It sported a long stem and bulbous cup-like structure, or calyx, near its top, which enclosed a unique filter feeding system and gut, according to an analysis of more than 1000 fossils reported this month in PLoS ONE. A small disc at the base of the stem anchored the animal to the sea floor, as the animal ate algae or pieces of detritus in the water. Siphusauctum lived in large clusters, so researchers nicknamed the region of the shale in which it was found Tulip Beds. It is not the only peculiar organism in phylogenetic limbo found in the Burgess Shale, however. Twenty other so-called "problematica" have eluded classification.
See more ScienceShots.