Officially named Siphusauctum gregarium, fossils reveal a tulip-shaped creature that is about the length of a dinner knife (approximately 20 centimetres or eight inches) and has a unique filter feeding system.
Siphusauctum has a long stem, with a calyx – a bulbous cup-like structure – near the top which encloses an unusual filter feeding system and a gut. The animal is thought to have fed by filtering particles from water actively pumped into its calyx through small holes. The stem ends with a small disc which anchored the animal to the seafloor. Siphusauctum lived in large clusters, as indicated by slabs containing over 65 individual specimens.
Lorna O’Brien, a PhD candidate in the Department of Ecology and Evolutionary Biology at the University of Toronto and her supervisor Jean-Bernard Caron, curator of invertebrate palaeontology at the Royal Ontario Museum, report on the discovery today in the online science journal PLoS ONE.
“Most interesting is that this feeding system appears to be unique among animals. Recent advances have linked many bizarre Burgess Shale animals as primitive members of many animal groups that are found today but Siphusauctum defies this trend. We do not know where it fits in relation to other organisms,” said O’Brien.