Pandorina is a genus of green algae characterized by colonies composed of 8, 16, or occasionally 32 cells held together at their bases within a globular colony enveloped in mucilage. The individual cells are ovoid or slightly narrowed at one end, resembling keystone- or pear-shapes. Each cell possesses two flagella and two contractile vacuoles at their base, along with an eyespot and a large cup-shaped chloroplast containing at least one pyrenoid. The colonies exhibit coordinated flagellar movement, creating a rolling swimming motion. Pandorina displays initial stages of colony polarity and differentiation similar to Volvox, with larger eyespots in the anterior cells. Molecular sequencing has indicated that Pandorina is paraphyletic relative to Volvulina. Asexual reproduction occurs through simultaneous division of all colony cells, forming autocolonies that are released when the colonial envelope gelatinizes. Sexual reproduction involves the division of each cell into 16-32 zoogametes, which exhibit heterogamy—pairs that fuse to form a smooth-walled zygote show slight differences in size and motility.