Because it is a single cell. Also, apparently a single cell on earth can get up to 2 inches in diameter: http://en.wikipedia.org/wiki/Valonia_ventricosa http://

Because it is a single cell. Also, apparently a single cell on earth can get up to 2 inches in diameter: http://en.wikipedia.org/wiki/Valonia_ventricosa http://en.wikipedia.org/wiki/Valonia_ventricosa