Commodity money coins. Commodity money Commodity money is money whose value comes from a commodity of which it is made. Commodity money consists of objects that have value in themselves (intrinsic value) as well as value in their use as money. Examples of commodities that have been used as mediums of exchange include gold, silver, copper, salt, peppercorns, tea, large stones (such as Rai stones), decorated belts, shells, alcohol, cigarettes, cannabis, silk, candy, nails, cocoa beans, cowries and barley. These items were sometimes used in a metric of perceived value in conjunction to one another, in various commodity valuation or price system
Buoyancy compensator, which is a variable volume buoyancy bag which is inflated to increase buoyancy and deflated to decrease buoyancy. The desired condition is usually neutral buoyancy when the diver is swimming in mid-water, and this condition is unstable, so the diver is constantly making fine adjustments by control of lung volume, and has to adjust the contents of the buoyancy compensator if the depth varies. If the weight of an object is less than the weight of the displaced fluid when fully submerged, then the object has an average density that is less than the fluid and when fully submerged