This is a hydromedusan jelly, a species of Aequorea and one in which the radial pattern within the bell is actually the reproductive gonads of the jelly, liberating, when sexually mature, eggs, into the water column, for both fertilization and dispersal. Left of centre is a tentacle that has caught a copepod crustacean, which it is hauling up to the underside of the bell. There it will engage it with the mouth-like manubrium, and, thereafter, to the central stomach, for digestion and deployment of energy to the extremities of the jelly's body.
Lizard Island, Australia (2004)
Nikon F4 | Micro Nikkor 105mm f2.8 | Fuji Velvia