Microorganisms belonging to the genus Thioploca, for example, use nitrate, which is stored intracellularly, to oxidize sulfide, and have developed vertical sheaths in which bundles of motile filaments are located. It is assumed that Thioploca uses these sheathes to move efficiently in a vertical direction in sediment, thereby accumulating sulfide in deeper layers and nitrate in upper layers.[26] For some MTB, it might also be necessary to perform excursions to anoxic zones of their habitat to accumulate reduced sulfur compounds.