graptolite

From Ancient Greek γραπτός (graptós, “painted, marked with letters”) +‎ -lite.

• (UK) IPA^(key): /ˈɡɹaptəlʌɪt/

graptolite (plural graptolites)

1. 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.

• sicula
• prosicula
• rhabdosome