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Webster 1913 Edition

Noun.

[NL, Graptolithus, from Gr. [GREEK] is engraved, written (

γράφειν

to write) + [GREEK] 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.

graptolite ‎(plural graptolites)

Any of a group of extinct aquatic colonial invertebrates, of the class Graptolithina, from the Cambrian and Carboniferous periods
- 2004, Richard Fortey, The Earth, Folio Society 2011, p. 70:
  The samples were black shale, and on the shales were some ancient fossils called graptolites.