sea blubber

noun2

1. •
   A jellyfish; a medusa.
2. •
   A lion's mane jellyfish (Cyanea capillata).

   • No less remarkable for its beauty is Cyanea fulva. This species may well be termed the "little brown brother" of the more widely known C. arctica, or sea blubber, the largest jellyfish in existence. — 1923