A death assemblage of priapulid worms from the Middle Cambrian Burgess Shale

A slab of Burgess Shale (Middle Cambrian), displaying an incomplete exoskeleton of the large arthropod Sidneyia inexpectans and encompassed by nine specimens of the priapulid worm Ottoia prolifica, is interpreted as a death assemblage, with the worms once living off or feeding around a carcass or freshly moulted instar of Sidneyia. Death is thought to have been caused by an obrution event that preserved the organisms in situ.