Most marine worms are polychaetes. A quadrat is a square frame of any size that can be placed randomly or along a transect line. The organisms within the square are counted or measured. This life zone is submerged at every high tide and is dominated by brown seaweed, such as knotted wrack and rockweed. For this reason this zone is often called the brown zone.
Sedimentary rocks form when sediments accumulate and are then consolidated.
Sedimentary rocks are formed either from pieces of pre-existing rock or are precipitated chemically. Sandstone and shale are examples of sedimentary rocks formed from pieces of other rocks and evaporites and coal are examples of precipitated sedimentary rocks. One of the long sides of the net is weighted and the other long side has floats. The net is pulled through the water by the short sides so that the side with floats rides on the surface and the weighted side moves along the bottom. The system includes a septic tank where solid sewage is broken down by bacteria and a leach field into which water flows from the tank.