These freshwater bacteria grow in colonies which take the form of dark green, gelatinous spheres with a smooth surface like a plum.

It is common and widely distributed both geographically and ecologically in oligotrophic and mesotrophic freshwaters in temperate and sub-Arctic regions.

In contrast, in a cold (4 °C), nutrient-poor spring in Oregon, USA, N. pruniforme reached a handball size of 15–17 cm in diameter and weighed 2.6 kg after sustained slow growth for 9–14 years.

[2] Very large colonies are also found in cold transparent lakes in Greenland (K. Sand-Jensen, unpubl.

In addition to their larger size and persistence, they differ from Danish temperate specimens by having a more solid surface and a denser gel.