Creative Commons photo by Nuwandalice is licensed under CC BY 2.0

How to care for delightfully charming Marimo moss balls

Kier Holmes

One part mysterious, the other part charming, Marimo moss balls resemble fuzzy dog toys but are actually a rare form of spherical algae that are worth knowing about. Marimo translates to “ball seaweed’ in English. And that’s exactly what they are, solid balls of algae growing very slowly outward that live for 100 or more years.

Not only do they make great heirlooms to pass down, but also they are believed to mend relationships. According to Japanese folklore, when a tribal chief forbade his daughter and her lover to be together, the star-crossed pair consequently fell into the water where their hearts became Marimo balls. As an extension of this folk tale, Marimos are considered the “love plant” in Japan because the algae are believed to be able to see true love. Whether you believe this lore or not, all you need is one touch of the plush, velvety surface to get hooked.

Marimo balls are unique as a decorative element displayed in a vessel with colored gravel and small shells. They also make for a thoughtful gift.

Care is unbelievably simple. Follow these steps:

  • Place your Marimo where it receives low to medium light and cool temperatures. Direct sun is disliked and will result in browning.
  • Change the water every two weeks using filtered water, and clean the container if algae builds up. No fertilizing needed.
  • In general Marimos are well behaved, but to keep them round, gently move the water to mimic the subtle waves of a lake (their native habitat).
  • These green charms can mingle with fish in a freshwater aquarium, but watch out for potential snacking by finned friends. Snails, on the other hand, avoid them.