Marimo moss balls are charming, fuzzy and popular. But they’re not made of moss. They’re living algae that can be found at the bottom of cold lakes in Japan and Iceland, and are formed by water currents that rock them gently back and forth into a sphere. Marimo (pronounced ‘mar-ee-moh’) can live for a long time—some have been found that are believed to be 100 years old. They grow, but just a little bit each year. In Japan, some marimo balls are handed down from one generation to another. Easily cultivated, they’ve become popular in the United States where they’re sold for use in glass jars and aquariums as a decorative plant element, or as “pets” because you can stroke their velvety filaments, give them a little squeeze and gently roll them around in your hands. It’s also helpful to slosh the water around in their tank to mimic a natural water current.
They require medium indirect light (direct sunlight will turn them brown), cool water that gets changed every few weeks and the occasional tank cleaning if algae grows on the walls of the container. They can be kept in an aquarium with fish (but not all kinds—some like goldfish tend to overeat the algae), or alone in a glass vase or even a simple canning or apothecary jar. You can purchase marimo online or at some local aquarium supply stores, but beware of fakes. Real marimo are unique—no two are alike—and tend to be small (a ball that’s 2 inches in diameter might be 8-15 years old) and composed of solid algae. Fakes are often algae wrapped around a styrofoam ball or are made out of pieces of algae. They won’t live as long as the real thing and won’t have the same natural, spongy appearance or feel. Here’s a sampling of a few of the 27,000 marimo posts from Instagram.
Keeping it simple with marimos of different sizes using rocks and glass creates an aquarium look(sans fish). The smaller containers would be good desk companions as they can thrive under the fluorescent or full spectrum lights that many offices have.
This collection of large marimo look otherworldly and modern floating in a simple glass vase.
This charming acquarium has a betta fish that’s marimo-friendly, plus a buddha, Brazilian penny, wort plant and faux coral making it a soothing and pretty vignette.
This terrarium pendant can be worn and the movement is sure to make the tiny marimo happy.