Not only is it not a jellyfish, it's not even an "it," but ... Man-of-wars are also known as bluebottles for the purple-blue color of their pneumatophores. The tentacles are the man-of-war's ...

Sea nettle jellyfish are white or blue in color in Hilton Head area waters ... Shore Beach Services flies a purple flag on the flagpoles and on the red Beach Patrol trucks. Wagner also noted ...