Pictured at The New England Aquarium, Boston

Sea jellies are not just floating, stinging lumps of slime.
Mistakenly called jellyfish, sea jellies are not fish at all. Jellies have no
backbone, no brain, no heart, and are 95% water. Out of the water, they are
shapeless gelatinous blobs often found on the beach after a rough storm.
Underwater, however, they are beautiful, graceful swimmers.

Sea jellies have lived for millions of years.
Fossils have been found in 650-million-year-old rocks off the coasts of
England, South Africa and Australia. Today, jellies live in all oceans and
in some freshwater rivers and lakes.