Diatom

One of the Diatomaceae, a family of minute unicellular Algae having a siliceous covering of great delicacy, each individual multiplying by spontaneous division. By some authors diatoms are called Bacillariae, but this word is not in general use.

A particle or atom endowed with the vital principle.

microscopic unicellular marine or freshwater colonial alga having cell walls impregnated with silica