Does anyone know this jellyfish by name?

A reader from the UK sent me these lovely photos that he took of a jellyfish and asked for my help in identifying it. Unfortunately, while I'm pretty good with bacteria, plants, and tropical fish, my taxonomy skills don't go much farther unless I have a sample of DNA.

These photos were taken at La-Manga off the coast of southern Spain.

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My Sciblings have guessed: Rhizostoma, Stomolophus meleagris, or Mastigas

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If you know, we'd all appreciate an answer in the comments.

And if you don't know about much jellyfish, RPM at evolgen would like your help answering a different reader's question: When a manatee swims, does it get water up its up nose?

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I'd have to go with Rhizostoma pulmo. The look and the location are right. There's also a similar beastie that hangs around the UK called Rhizostoma octopus.

rhizostoma pulmo

Thats definately the one that sung me in the Mar Menor,La Manga !!

I swam into it whilst snorkling just INSIDE the safety nets (yeh right!) and I thought I'd swam into a plastic bag until my face HURT !!

I swam to shore quicker than Phelps !!