The thyroid gland plays a critical role in the metabolism, growth, and development of the human body. It assists with many body functions by releasing appropriate amounts of thyroid hormones into the bloodstream depending the situations. This gland is found at the front of the neck under the voice box and has the shape of a butterfly (the two side lobes lie against and around the windpipe, connected at the front by a narrow strip of tissue). The thyroid gland produces three hormones: triiodothyronine (T3), thyroxine (T4), and calcitonin. Hormones T3 and T4 increase the basal metabolic rate instructing cells in the body to work harder so they can use up more energy. Iodine is one of the main building blocks of both hormones. This element needs to be acquired through diet, seaweed being one of the best natural sources of iodine. Calcitonin is made by C-cells. It is involved in calcium and bone metabolism.