Alien Stingers at the New York Aquarium

Stingers, including jellies and sponges, are the simplest mulitcellular creatures capable of movement and feeling (i.e., they have nerves and muscles), according to the Alien Stingers FAQ. This exhibit at the New York Aquarium explains how such creatures eat, breath, move, and breed, but the real draw is the stingers themselves, floating almost rhythmically in their dark pools.