A plump fossil priapulid worm is preserved flattened on a dark shale surface. The annulated trunk is strongly curved into a hook shape, with the narrower anterior region at the right end. The entire fossil appears as a golden brown film in this image. A lighter coloured linear trace marking the gut tract runs from the anterior end (where the proboscis is withdrawn) to the posterior tip. This is one of many fine specimens of Ottoia prolifica in the Invertebrate Palaeontology collections of the Royal Ontario Museum. For more details, see: https://burgess-shale.rom.on.ca/fossils/ottoia-prolifica/

Ottoia prolifica: a stem-group #priapulid #worm, ~7 cm in length, from the world famous #BurgessShale in #BritishColumbia 🇨🇦. Strongly annulate trunk, anterior to right w retracted proboscis & introvert hooks; pale linear trace along inner curve = gut #Cambrian (~508 MYA) #WormWednesday #fossil