The advice varies on how often to change the water, but every few weeks should do. If you have a fishtank (not goldfish though, they tend to tear marimo apart) you can use the algae that is the marimo moss ball to fight the kind of algae you don't want in your water. As James says, the advice is to use soft water but they seem to cope just fine with my hard-ish tap water.

They arrived in a damp plastic bag and initially took up residence in an old pickle jar, but now I've found a more salubrious home for them, as you can see in the picture above. I bought three largish balls on eBay, (they cost £3.99), but you can get them from various online stores and from aquatic specialist shops. Intrigued, I decided to get some marimo of my own. It's the Japanese who have really embraced marimo as part of their culture: there's a fantastic blogpost about it at, including the very bizarre (to my British eyes) mascot of the Hokkaido prefecture of Japan, Marimokkori, with an unfortunate bulge in his trousers.Īnyway, moving swiftly on. It's a species of filamentous green algae - Latin name Aegagropila linnaei - that lives in lakes in various countries from Scotland to Japan, but only where conditions are just right.

'Marimo' means 'seaweed ball' in Japanese, but it's not seaweed either.

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