noun
graptolite
An extinct marine invertebrate from the Paleozoic era; a technical term in paleontology.
フデイシは古生代の示準化石として重要だ。
Graptolites are important as index fossils of the Paleozoic era.
この地層からフデイシの化石が多数見つかった。
Many graptolite fossils were found in this stratum.
From 筆 (fude, 'brush') + 石 (ishi, 'stone'), referring to the brush-like appearance of the fossil.