Mercury is a chemical element with an atomic number
Mercury forms numerous organic compounds, many salts, etc.
Out of all the sources Methylmercury is majorly found in our foods.
Methylmercury is formed when Mercury reacts with Carbon, and further attaches with water to enter in soil, lakes, rivers, and oceans and hence contaminate all the food sources.
Mercury has generally found in sea animals such as fishes.
The most common Mercury-containing food sources are: Swordfish, Shark, Tilefish, Orange-roughy, Marlin, etc.