I find Pandorina morum very frequently, both in the plankton and among floating or decomposing aquatic plants. This volvococcal alga is particularly common in spring.

The colonies of Pandorina morum appear very compact because the cells are arranged without a gap in the gelatinous matrix. Their shape is therefore wedge-shaped and not round (s. fig. 2 b). Two flagella of equal length arise at the apical end and pierce the gelatinous envelope through two short canal (s. fig. 1 b). At their base are two contractile vacuoles and an orange-red eyespot (s. figs. 1 a and 2 a). The chloroplast shows a characteristic striation (s. fig. 2 a).

Pandorina morum is often confused with the equally common volvococcal alga Eudorina elegans. However, the colonies of Eudorina elegans are considerably larger (50-200 µm) and the round cells are clearly separated from each other.