The Cannonball jellyfish, known scientifically as Stomolophus meleagris, is a medium sized jellyfish with a dome-shaped top that resembles a cannonball. The Cannonball jelly is also known as a cabbagehead jellyfish. The Cannonball jellyfish is most commonly found off the eastern coast of the United States and the Caribbean, but it can also be found in the Pacific. In the Pacific, the rim of the Cannonball jellyfish can be rimmed with blue, but elsewhere it is usually rimmed with brown. Although usually only a source of a mild sting for humans, there is a chance that the toxin the Cannonball carries in its nematocyst can cause cardiac issues.