Conodonts (Greek kōnos, "cone", + odont, "tooth") are extinct chordates resembling eels, classified in the class Conodonta. For many years, they were known only from tooth-like microfossils found in isolation and now called conodont elements. Knowledge about soft tissues remains limited. The animals are also called Conodontophora (conodont bearers) to avoid ambiguity.
Conodont teeth are the earliest found in the fossil record. Neil Shubin writes: "For a long time conodonts were enigmas: scientists disagreed over whether they were animalian, plant or mineral. Conodonts were claimed to be pieces of clams, sponges, vertebrates, even worms. The speculation ended when whole animals started to show up in the fossil record. For years, paleontologists have argued about why hard skeletons, those containing hydroxyapatite, arose in the first place. For those who believed that skeletons began with the backbones, or body armor, conodonts provide an 'inconvenient tooth' if you will. The first hydroxyapatite-containing body parts were teeth. Hard bones arose not to protect animals but to eat them.