(Greek: hidden, secret, secrets, secret writing; by extension, applied to secret code or ciphers)
Many of them can be found in any sample of wet soil; a large part of the cryptozoa has not yet been identified by science.
The earliest rocks on earth with elaborate fossils are said to belong to the "Cambrian age"; and the entire four-billion-year history of our planet that preceded it has been, until recently, dismissed as the "pre-Cambrian age". Now that the traces of life have unmistakably been found in it, the more appropriate name Cryptozoic eon (hidden life) is used, while the last 600 million years make up the "Phanerozoic eon" (visible life).
The Cryptozoic eon is even divided into two sections:
The earlier "Archeozoic era" (ancient life), to which the first traces of unicellular life belong, and the later "Proterozoic era" (early life).
The "zygomatic arches" are formed by the temporal process of the zygomatic bone (bone which forms the prominence of the cheek) that joins the zygomatic process (arch of bone beneath the orbit) of the temporal bone or the large irregular bone situated in the base and side of the skull.
A cross reference of other word family units that are related directly, or indirectly, to: "secret, hidden, confidential, concealed": ceal-; clandesti-; myster-; occult-; orgy; stego-, stegano-.