I went for a dive last night and saw a jelly that was about 600mm in diameter. I used my arm to compare underwater for later reference so very certain of size.
It had what looked like clear sea tulip like growths out of the top of the cap and the "mane" was about 6-700mm projecting below the cap, I couldnt see any tendrils.
I've never seen a jelly that big.
Need to get a little POS camera for these sort of things..
Any idea on identification?