These large jellyfish swarm in warmer coastal waters in late spring and often wash up on our beaches in May or June, sometimes in their hundreds. Their favourite meal is plankton, which can be found in shallow waters. This is what often causes them to wash up, as they underestimate their size. They have eight frilly arms, which contain their small stinging tentacles and surround hundreds of little mouths! The sting of the barrel jellyfish is not normally harmful to humans, though if you find one on the beach it's best not to handle it as they can still sting when dead.

A large translucent jellyfish with a huge mushroom shaped bell and a bunch of 8 frilly tentacles below. They don't have marginal tentacles but do have a violet fringe around the bell which contains sense organs. They are often found washed up on beaches in May and June.
This one was swimming under a bridge in about 2ft of water, note the scrap wood and coachbolts etc on the bottom.

Best in large.