Earwax or even a piece of hair could be lying on top of the eardrum and when the eardrum vibrates, it may cause funny noises (just like a piece of string on a lightly beating drum). Obviously, treatment is by removal. Eustachian Tube Dysfunction can also cause crackling/popping noises.
Adverse Reactions to Elemental Iron Supplements Meeting your daily iron recommendation is important, and you may have to take supplements to get what you need. Iron's primary function is carrying oxygen through your blood and delivering it to cells, tissues and all of your organs.
However, its use only became widespread in the 14th century, when smelting furnaces (the forerunner of blast furnaces) began to replace forges. Iron ores are rocks from which metallic iron can be economically extracted. These rocks are usually found in the form of hematite (Fe2O3) or magnetite (Fe3O4). About 98% of world iron ore production is used to make iron in the form of steel.