Rhizostoma pulmo

Osaka Aquarium

Still from "Antarctic Treasure: The Underwater Images of Norbert Wu"

Update: Found the original source, the photographer Arne Kuilman. Link to his Flickr page.

Credit American Scientist

Incredible how these animals are so tenuous and can still leave a fossil record

Photographer's Flickr page

link

Flickr link

Thousands of Giant Jellyfish in Britain Coast (8 year old article)

More pics in article link

Original text from french:

In the waters off the English coast, huge jellyfish have been found and captured by photographer Steve Trewhella who works for the Daily Mail. Jellyfish "Rhizostoma pulmo" are known for their giant size but also for being harmless; the photographer was therefore able to swim alongside them.

Jellyfish Encounters in California By Mike Bartick

link