noun
foraminifer; foraminiferan
A type of single-celled marine organism with a perforated shell; used in biology and paleontology.
有孔虫の化石は地層の年代を決めるのに使われる。
Foraminifer fossils are used to determine the age of geological strata.
From 有 (having) + 孔 (hole) + 虫 (insect/worm), referring to the perforated shells of these organisms. The exact historical derivation is uncertain.