Rhopalium

Rhopalia (singular rhopalium) are sensory structures of jellyfishof the class Scyphozoa. They include specialized structures for sensing light (ocelli), or movement or direction with respect to gravity (statoliths). The 'eyes' are most complex in the Cubozoa, resembling the image-forming eyes of squid, octopi, and vertebrates.

External links:

• The Jellyfish homepage - University of New South Wales
• The Tree of Life - Cnidaria