Pandorina is a genus of green algae composed of 8, 16, or sometimes 32 cells, held together at their bases to form a sack globular colony surrounded by mucilage.

Each cell has two flagella with two contractile vacuoles at its base, an eyespot, and a large cup-shaped chloroplast with at least one pyrenoid.

The colonies co-ordinate their flagellar movement to create a rolling, swimming motion.

Pandorina shows the beginnings of the colony polarity and differentiation seen in Volvox, with the anterior cells have larger eyespots.

Zoogametes show indications of heterogamy, a slight difference in the size and motility of the pairs that fuse to form the smooth-walled zygote.