Scientific name

Aegagropila Kützing

Common names

marimo, lake ball, moss ball



Similar genera


Native distribution

palaearctic distribution; widespread in Japan, restricted to previously glaciated areas of Europe

Species cultivated

Aegagropila linnaei Kützing

Adventive distribution

information not available

Weed status

information not available


submerged, typically and most known as a free-floating ball

Brief description

Green macroalga; similar to Cladophora Kützing. Spherical growth form is a radially organized collection of single plants; attached growth form is irregularly organized. Filaments uniseriate, stiff, profusely branched; rhizoids often with terminal finger-like projections. Cell shape and size irregular, thick walled, chromatophores dense. Dispersal by fragmentation and 'rolling' across floor of water body.

Natural habitat

brackish or freshwater, oligo–mesotrophic lakes; only attached form in dystrophic and slightly eutrophic habitats

Additional comments

The spherical growth form of Aegagropila linnaei is produced by a mixture of mechanic processes through water motion and features intrinsic to the species. This form requires abundant light and is sensitive to eutrophication.

Aegagropila linnaei superficially resembles Cladophora (Boedeker et al, 2010). Little genetic variation was found in biogeographical studies, indicating that A. linnaei is truly a single species (Boedeker et al., 2010).