Frustules

Part of speech: noun

Definitions

1. The minute and often glass-like structures that serve as the protective casings for specific aquatic microorganisms are crucial for their survival
2. These delicate, silica-rich formations act as natural armor for several species of single-celled algae and protozoa
3. Tiny, rigid shells made of silica that enclose and protect specific types of single-celled aquatic organisms

Etymology: Latin "frustum" meant a piece broken off something, a fragment or morsel. Its diminutive, "frustulum," meant a little fragment, and that is the root of the English term. Scientists chose it for the silica case around a diatom, a single-celled alga, because the case looks like a small broken piece of glass or pottery. Diatom cases are built in two halves, one fitting over the other like the lid and base of a petri dish. The overlapping halves are what the name points to, since the Greek "diatomos" means "cut in two." Both words share the idea of division, though one points to the whole cell and the other to the fragment that remains.