Earth formed around 4.54 billion years ago by accretion from the solar nebula. Volcanic outgassing probably created the primordial atmosphere and then the ocean; but the atmosphere contained almost no oxygen and so would have been toxic to most modern life including humans.
Euthyroid is the state of having normal thyroid gland function. Examples of a nonfunctioning thyroid gland may be hypothyroidism, hyperthyroidism, or thyroiditis.
Steroid Definition: A steroid is a terpenoid lipid that is characterized by having a carbon skeleton formed from four fused rings.The rings typically are arranged in a 6-6-6-5 manner. Steroids are distinguished from each other based on the functional groups that are attached to the rings.teroid Definition: A steroid is a terpenoid lipid that is characterized by having a carbon skeleton formed from four fused rings.