Ay-O, known as the "rainbow artist", for his use of colorful, rainbow-striped motifs in his artwork to break through the constructs of painting. Other aspects of Ay-O's activities include experiments with tactile and other perceptual art, events with the international avant-garde art movement Fluxus, and printmaking throughout his life. His choices in various places of different environments, makes him a precursor of today's Happenings and installations. The "Hydrā", made in 1961-62, is a device made of a cylindrical aluminum body with light bulbs situated within six lanterns, and is associated with the multi-headed serpentine in Greek mythology. The light bulbs inside the lanterns, emit an artificial light and the upward airflow generated by the heat acts on the propellers causing the mounted lanterns around the shaft, to rotate in a natural phenomenon. The light overflowing from the lanterns reflects on the movement of the rotating lanterns. It then transfers on to the main body of the work, the aluminum plate, creating a fluid pattern reminiscent of intertwining snakes in a light spectacle on the walls and ceiling of the exhibition room. "Hydrā" is installed in the first half of the 5th exhibition room and every object located within the space is enveloped by the light created by this device, becoming a piece that is part of Ay-O's environmental art.