CONODONT
conodont
(noun) small (2 inches long) extinct eellike fish with a finned tail and a notochord and having cone-shaped teeth containing cellular bone; late Cambrian to late Triassic; possible predecessor of the cyclostomes
conodont
(noun) the tiny fossil cone-shaped tooth of a primitive vertebrate of order Conodonta
Source: WordNet® 3.1
Etymology
Noun
conodont (plural conodonts)
Any of several extinct fish-like chordates having cone-like teeth.
A microfossil tooth of such an animal.
Source: Wiktionary
Co"no*dont, n. Etym: [Gr. (Zoöl.)
Definition: A peculiar toothlike fossil of many forms, found especially in
carboniferous rocks. Such fossils are supposed by some to be the
teeth of marsipobranch fishes, but they are probably the jaws of
annelids.
Source: Webster’s Unabridged Dictionary 1913 Edition