It is quite fitting that Omanyte is the symbol of the Worldwide Association of Paleontology, headquartered in Pewter City; no other fossil would be nearly as suitable.
Although the term Omanyte is nowadays used primarily for O. omanyte, the most common and only one (as of this writing) to be successfully revived, an astounding variety of genera and families are known in the fossil record. Their shells are remarkably impervious to the ravages of time: while most Lazarus pokemon are only rock-types because of the nature of their revival, Omanyte shells are believed to have been made of some type of stone throughout most if not all (for the fossil record is never complete) of prehistory. But for all their immense documentation, when compared to the Treecko who grew feathers and evolved into Normal/Flying pokemon, or the relatives of Mudkip who first crawled onto the land, these pokemon have changed little throughout the centuries.
Therefore, for all their iconic status among fossils, despite being the first to be raised from extinction, Omanyte would be a weak symbol if not for the shape of their shells. They are called the spiral pokemon, and their strange shape has been subject to a great deal of speculation, more often from philosophers than from paleontologists themselves. Some have even said that Omanyte are powered not by food or sunlight, but by spiral energy; the power of evolution, the power of life itself. This claim seems a spurious one, but it should be remembered that vast quantities of fossil fuels are always found near rock formations containing Omanyte shells. Humanity, too, uses the helix to run the engines of civilization.