Stomolophus meleagris, otherwise known as the cannonball jellyfish, is a species of jellyfish that resembles a cannonball in both shape and size. It has oral arms underneath its body that extend out around the mouth. This species feeds mainly on zooplankton and has a symbiotic relationship with the portly spider crab, which also feeds on zooplankton. Like most cnidarians, the cannonball jellyfish can reproduce both sexually and asexually.