Marimo – The Extremely Rare Algae Balls That Make Great Low-Maintenance Pets

Marimo is a rare growth form of the Aegagropila linnaei algae in which the aquatic plant grows into large green balls with a velvet-like texture and appearance. It’s also a natural treasure of Japan, as well as a popular pet.

Aegagropila linnaei algae has long been a mystery in biology, particularly due to its fascinating spherical growth form. The algae can be found in just a handful of aquatic environments located in four countries – Iceland, Scotland, Estonia, and Japan – and exists either as free-floating filaments, flat growths on rocks or green balls that can reach up to 40 cm in diameter. It’s the latter that has fascinated both scientists and algae enthusiasts for centuries.

Marimo (literally “ball water plant”) are particularly popular in Japan. The largest and most impressive-looking ones can be found in  Lake Akan, in east Hokkaido. For some reason, given enough time marimo her grow up to 40 cm in diameter, much larger that the moss balls found anywhere else. The lake is shallow, providing the conditions needed for Aegagropila linnaei to thrive, so the bottom is full of these giant, fluffy balls just waiting to be squeezed. Only you’re not allowed to take those!

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