From the BBC:
Rare jellyfish spotted off coast
A rare type of jellyfish has been photographed for the first time off the South West coast.
The orange-pink creatures, called Apolemia uvaria but also known as “pearl strings“, have been seen off Plymouth and the Cornish coast.
But people have been warned not to touch them as they have a nasty sting.
Rory Goodall, a wildlife trip operator in Penzance said: “I have seen thousands of them attracted to our waters because of plankton.”
See also here.
Pelagia noctiluca jellyfish in the Mediterranean: here.