diatom

Etymology

From (deprecated) genus name Diatoma, from Ancient Greek διάτομος (diátomos, “cut through, cut in half”).

noun

1. Any of a group of minute unicellular algae having a siliceous covering of great delicacy, now categorized as class Diatomophyceae or division Bacillariophyta.
   Diatoms are enclosed in two shells that fit together like a pillbox. 1967, George K. Reid, edited by Herbert S. Zim and George S. Fichter, Pond Life, New York: Golden Press, →LCCN, →OCLC, page 31
   Diatoms are characterized by a cell wall called a fistula made of silica, which usually has two overlapping sections. 2012, Caspar Henderson, The Book of Barely Imagined Beings, Granta Books, published 2013, page 287