Sediment traps are cone-shaped or cylindrical collectors that catch detritus as it sinks down from the surface ocean to the deep sea. This material is made up of dead phytoplankton and zooplankton, the feces of zooplankton and fish, and many other different kinds of detritus. This material, often termed marine snow, is an important food source for organisms that live in the deep sea, as well as a mechanism for transporting material from the surface waters to the deep sea where it is eventually decomposed by bacteria. The sediment traps are attached to a line that has floats on the surface and a weight at the bottom to keep it vertical. Some sediment traps have subsurface floats and a bottom weight that actually rests on the sea floor. After several days or weeks, oceanographers recover the traps, weigh the particulate material therein, and analyze the material's chemistry. The quantity of material divided by the collection area and the time the traps were deployed gives the particle "flux".