What is "graptolite"

Graptolite \Grap"to*lite\, n. [NL, Graptolithus, from Gr. ? is engraved, written (gra`fein to write) + ? stone.] (Paleon.) One of numerous species of slender and delicate fossils, of the genus Graptolites and allied genera, found in the Silurian rocks. They belong to an extinct group ( Graptolithina) supposed to be hydroids.

1838, from Modern Latin graptolithus, literally "written-stone," from Greek graptos "engraved, written, painted" (verbal adjective of graphein; see -graphy) + lithos "stone" (see litho-). So called because the fossils resemble writing.

n. Any of a group of extinct aquatic colonial invertebrates, of the class ''Graptolithina'', from the Cambrian and Carboniferous periods