Phacotus is a genus of green algae in the family Phacotaceae.

[1] Phacotus is a green alga found in freshwater environments, characterized by its calcite lorica, which can be plentiful in temperate hardwater lakes.

The lorica displays two slightly different appearances under cross-polarized light; one of these may occasionally feature a red ring near the perimeter.

[2] This difference could represent the outer and inner views of the loricae, as they typically separate after the organism's death.

This Chlorophyceae-related article is a stub.