December 23, 2006 From Scum, Perhaps the Tiniest Form of Life By WILLIAM J. BROAD The smallest form of life known to science just got smaller. Four million of a newly discovered microbe — assuming the discovery, reported yesterday in the journal Science, is confirmed — could fit into the period at the end of this sentence. Scientists found the microbes living in a remarkably inhospitable environment, drainage water as caustic as battery acid from a mine in Northern California. The microbes, members of an ancient family of organisms known as archaea, formed a pink scum on green pools of...