The mooring style used on this buoy is a jetting cone and wire rope. This is an inexpensive method of keeping a buoy on station. The cone is "jetted" about 15 to 20 feet down into the mud. The concave shape increses the resistance which increases their holding power.
This is a jetting cone on the end of the jet pipe. The cone is made of steel and is about 4 inches in diameter. They cost about $3 each and provided they can be jetted in deep enough, hold as well as a 1000lb concrete sinker and at a much lesser price. The wire rope is attached to the cone using a wire rop clip or "Bug" as it is referred to by the buoy tender crew.