Rhizostoma pulmo, commonly known as the barrel jellyfish, the dustbin-lid jellyfish or the frilly-mouthed jellyfish. , is a scyphomedusa in the family Rhizostomatidae. It is found in the northeast Atlantic, and in an Adriatic, Mediterranean Sea, Black Sea and Sea of Azov. It is also known from the southern Atlantic off the western South African coast and into False Bay. It is a favourite food of the leatherback turtle.