A strange fossil in the Museum in the Park

On one of my many odd tasks today I visited Stroud's Museum in the Park to deliver some programmes for the film festival. One of the events will be a celebration of the films of a local animation studio most famous for creating 'Animal farm'. The museum will be showing a concurrent small exhibition about the company 'Halas and Batchelor' so I was enquiring about what they would be showing. I'm hoping to get some visual material to use in the window display about the festival, possibly some of the individual cells made by the animators.

I was shown a specialised animator's editing machine and tried to take some snaps with my small camera but the light was terrible, a mix of shadow and reflections. But I spotted this unusual fossil in an adjacent gallery showcasing the local geology. I think it was found in cliffs formed by the River Severn estuary.