Round, green and fuzzy… it is a Marimo!

Hello everyone,

Today I would like to talk about a very “cute” plant. If you have an aquarium at home, I am sure you know this plant and probably you even have at least one. Today the plant I would like to talk about is a marimo! Even the name sounds kind of cute, right? So what is this plant?


This plant originally comes from Japan, Iceland, Scotland, and other lakes in the northern hemisphere – it literally means “seaweed ball”. Its scientific name is Aegagropila linnaei but people usually call it marimo or just moss ball. If you closer inspect these fuzzy balls you can see it has no roots, flowers, stem… no wonder it is a type of algae, which lives in colonies. In their natural habitat all they do is basically rolling around on the bed of a lake. The best you can imagine is like watching a Western movie and when you see a tumbleweed rolling around – well that is kind of how a marimo works too 🙂
It became lately very popular, because its round and fuzzy shape and people unfortunately disturb their natural habitat by taking them home. In made areas in Japan and Iceland the local government needs to protect these marimo colonies from tourism.

You can ask, if it is an algae, doesn’t it grow fast and reproduce, why protect algae?


The answer is, it isn’t an average algae. They grow really slow, about 5mm / year if conditions are good. That is really slow, and you can imagine how many years it takes to reproduce even 1 adult specimen.  Luckily you don’t need to steal them from nature. If you have an aquarium shop in your city there you can find marimo for sure, since they are pretty standard decorations for every home aquarium.

Now about their care and health. It is quite simple, you only need to follow some basic rules. They like to live in filtered or distilled water – just avoid chlorine. They don’t require space like an animal would need, so you can keep them in a small glass to a big one and decorate it with colorful stones or other plants. They like to be in a more cooler water and don’t require much sunlight. I keep them in my windowsill in the corner where they get a decent amount of sun. If the water gets warm just move it away from the window or exchange water. One in a while roll them around to ensure they will keep their round shape if you don’t do it, brown spots can occur. If you see brown spots don’t panic it can happen because of multiple issues:
– lack of light. Just roll the marimo around so it gets more light equally
– dirty water/marimo. Exchange the water and wash the marimo in distilled water gently
– water problem. Change the water. Try distilled water, it works for me perfectly

It can happen in some unfortunate situation that your marimo gets some infection. If brownness spreads rapidly try to save the rest of the green healthy part by gently taking off the healthy part from the unhealthy part. Then roll a ball and after years it will heal. By the way that is also how to multiply your marimo, although I don’t recommend it until you have a fairly big sized marimo.

All in all, the marimo is fairly simple to take care off. All you need is filtered/distilled water and light. If you wish you can also add fertilizer to the water, but it isn’t required at all. In the future if space and time will allow I want to extend my water based plant collection. If you have a marimo at home, let me know if you have any tips or tricks about their care in the comments! And as always thanks for reading!


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