Creepy things from beneath the sea are clichés of modern exploration, but the abyss has now produced a surprise so bizarre as to have touched off hot international debate: tiny, mysterious, apparently living creatures far smaller than any known bacterium -- so small as to strain the limits on what is needed for independent life. Their discoverers call them nanobes (pronounced NAN-obes), because their size is in the realm of nanometers (or billionths of a meter). At 20 to 150 nanometers in length, they are smaller than cells, smaller than fungi, smaller than the smallest known bacterium and roughly the same size as viruses, which are considered nonliving parasites because they need hosts to reproduce. Thus, nanobes call into question the minimum size requirements for terrestrial life.