"About the Shark, phlegmatical one, Pale sot of the Maldive sea, the sleek little pilot-fish, azure and slim how alert in attendance be. From the saw-pit of mouth, from his charnel of maw, they have nothing to dread. But liquidly glide on his ghastly flank or before his Gorgonian head: Or lurk in the port of serrated teeth in white triple tiers of glittering gates, and there find a haven when peril's abroad. an asylum in jaws of the Fates! They are friends; and friendly they guide him too prey, yet never partake of the treat -- eyes and brains to the dotard lethargic and dull, pale ravener of horrible meat." - Herman Melville
Evidence for the existence of sharks dates from the Ordovician period, 450–420 million years ago, before land vertebrates existed and before many plants had colonized the continents. Only scales have been recovered from the first sharks and not all paleontologists agree that these are from true sharks, suspecting that these scales are actually those of thelodont agnathans. The oldest generally accepted shark scales are from about 420 million years ago, in the Silurian period.