The prehistoric Helicoprion, which means "Spiral Saw," had a very unusual feeding apparatus that a scientist described as follows: "A permanently-tensed party favor studded with a fearsomely pointed dentition." The scientist was none other than geologist Alexander Petrovich Karpinsky who coined the name Helicoprion after discovering a whorl specimen in the Ural Mountains back in 1899.
These monsters of the deep possessed "tooth whorls" or spirally arranged clusters of the teeth in their lower jaw which gave their jaw a buzz saw-like appearance. Scientists think the tooth whorls helped in deshelling prey.
Estimated to have been between 20 to 25 feet in length, Helicoprion is an extinct genus of shark-like fish that lived during the Permian period: "Helicoprion is an extinct genus of whorl-toothed ratfish that first arose in the oceans of the Late Carboniferous, approximately 280 million years ago, and survived the Permian-Triassic extinction event, and eventually went extinct during the Early Triassic, some 225 million years ago."
Some confuse Helicoprion for a shark which is not the case as this excerpt explains: "Helicoprion was not a buzzsaw predecessor to great white or tiger sharks. The fish belonged to the lineage one branch over, near the evolutionary split where the ancestors of living sharks and ratfish parted ways."
In other words, Helicoprion was more ratfish than a shark.
Per reports, Helicoprion fossils have been discovered in many parts of the world: "Fossils of
Helicoprion bessonovi have been found in mid-Permian deposits in Russia, North America, Japan, and Australia, and, more recently, the Gufo Mountain one mile south of Zhijin city in Guizhou Province, China. A Helicoprion tooth whorl has also been discovered in the Late Permian Van Haven Formation, Ellesmere Island."