diatom: microscopic unicellular marine or freshwater colonial alga having cell walls impregnated with silica
alga: primitive chlorophyll-containing mainly aquatic eukaryotic organisms lacking true stems and roots and leaves
gladiolus: any of numerous plants of the genus Gladiolus native chiefly to tropical and South Africa having sword-shaped leaves and one-sided spikes of brightly colored funnel-shaped flowers; widely cultivated