graptolite
noun
grap·to·lite ˈgrap-tə-ˌlīt 
: any of an extinct class (Graptolithina) of hemichordate colonial marine animals of the Paleozoic era with zooids contained in conical cups along a chitinous support
Example Sentences
Recent Examples on the Web Surrounding remains—fossils of tiny, extinct marine animals called graptolites and conodonts—served as biomarkers to help confirm when the early scorpions wandered the earth. 
Katie Camero, WSJ, 16 Jan. 2020 One of the most emblematic animals of the Ordovician Radiation is the now-extinct graptolite. Annalee Newitz, Ars Technica, 21 Nov. 2017
Katie Camero, WSJ, 16 Jan. 2020 One of the most emblematic animals of the Ordovician Radiation is the now-extinct graptolite. Annalee Newitz, Ars Technica, 21 Nov. 2017 Word History
Etymology
Greek graptos painted (from graphein to write, paint) + English -lite — more at carve
First Known Use
1841, in the meaning defined above