Bubble algae (Valonia ventricosa)

   This unique tropical green alga is one of the largest single-celled life forms. It resembles a shiny, water-filled ball or "bubble" (sailor's eye) of a grass-green color, often growing alone, attached to coral substrate. Its surface is glossy, mirror-like, and glassy. Valonia ventricosa is a coenocytic organism consisting of only a single multinucleated cell.