Tweet this page Like this page Email this page Share this page Home» Resources » Identification » Identification of algae » Freshwater algae » How to identify algae » Identification guide » Unicellular » Cell wall has the form of a rigid clear box Cell wall has the form of a rigid clear box, either semi-rectangular “shoe-box” like, or circular “hat-box” like, with fine ornamentation; may move by gliding; chloroplasts brown 3. Please select cell shape. Circular (hat-box like) Semi-rectangular (shoe-box like)