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.
Definition of CHOROID. : a vascular membrane containing large branched pigmented cells that lies between the retina and the sclera of the vertebrate eye âcalled also choroid coat â see eye illustration. â choroid or choÂ·roiÂ·dal \kÉ-ËroÌi-dÉl\ adjective. See choroid defined for kids.