National Geographic : 1974 Mar
RICHARDB. HOOVER(ABOVE);CHARLESO'REAR(LOWERLEFT);JOHNS-MANVILLE CORPORATION Baubles from the sea's boutique, Corporation at Lompoc, California (be minute skeletons of silica (above) were low left), the diatomaceous earth makes crafted by diatoms, single-celled marine an exceptionally fine filtering agent. algae. Raining by the unimaginable A scanning electron microscope's view billions to the floors of ancient oceans, of the edge of a diatom's shell (below they compacted into deep sedimentary right) shows its porous particle beds. Here mined by the Johns-Manville trapping structure.