MASSACHUSETTS Diatoms
An assortment of diatoms from a sample of seawater photographed through a microscope at Harvard University. Diatoms are the silica skeletons of single-celled algae that flourish everywhere in fresh and salt water but are so tiny that 25 million would fit in a teaspoon. Some 70,000 species of diatom have been recognized so far. Photograph by Frans Lanting, www.lifethroughtime.com