Polytomella is a genus of green algae in the family Dunaliellaceae.

[1] Polytomella is a free-living, flagellated, nonphotosynthetic green alga with a highly reduced, linear fragmented mitochondrial genome.

[2][3] Polytomella, as it exists today, bears evidence of once having a functional photosynthetic plastid which has over evolutionary time changed such that it would appear now to have no genome or gene expressing mechanisms remaining to it.

[4] Having transitioned completely to heterotrophy, Polytomella uses organic acids, alcohols and monosaccharides as its carbon source.

[3][5][6] Despite being an evolutionary descendant of the green algae, Polytomella is a colourless organism because it has lost its photosynthetic ability.