Geograph - photograph every grid square

This specimen was about 300mm across (1 foot), lying on Borth beach, near one of the groynes. I think it had been dead for some time as it looked very battered. They really do look alien, especially when washed up on a beach.
Previously known as Rhizostoma octopus and commonly called the dust-bin lid jellyfish or barrel jellyfish, these creatures are quite common around Britain's west coast.
My thanks to Lodewijk van Walraven for correcting my previous faulty identification.