Moss Balls

Two completely different products are sold as moss balls, and knowing which one you want saves a wasted purchase.

The first is a living aquatic organism — a green sphere that sits in an aquarium, needs water, and is technically an alga rather than a plant. The second is a decorative object made from preserved plants that sits on a shelf and needs nothing at all.

We sell both kinds of moss ball. They have almost nothing in common beyond their shape.

Which Moss Balls Are You Looking For?

Live Marimo Moss Balls for Aquariums

Marimo moss balls are colonies of a filamentous green alga that grow into dense spheres, rolled into shape by water movement over years. They occur naturally in a handful of cold northern lakes — Lake Akan in Japan is the famous one, and there are populations in Iceland and Estonia.

Marimo moss ball growth is slow, on the order of a few millimetres a year, which is why a large one represents a long time. In an aquarium they are undemanding: low light, cool water, no substrate, no feeding. They absorb nitrates as they photosynthesise, which is a modest benefit to water quality rather than a substitute for filtration.

They are safe with fish and shrimp, and shrimp in particular graze the surface for the biofilm that collects on it — one of those relationships that makes a tank look busier than it is.

Sizes run from small spheres to specimens large enough to be the focal point of a tank. Full details, care and the size range are in Marimo moss balls for aquariums.

Decorative Preserved Moss Balls

Decorative moss balls are made in our workshop from preserved moss — reindeer lichen, cushion species, sometimes with ferns and dried elements worked into the surface — formed into spheres and finished by hand.

They do the job in a room that a bowl of green apples does on a kitchen table: they add colour and a rounded form to a surface without needing anything from you. They sit in bowls, on trays, along shelves, in groups of three at different sizes.

The material is preserved rather than living, so there is no watering, no light requirement and no maintenance of any kind. Indoors they hold their appearance for 7 to 10 years. See decorative moss balls.

Choosing a Size

For an aquarium, scale to the tank. A small sphere in a large tank disappears into the layout; a large one in a nano tank occupies half the visible space. Several small ones grouped on the substrate generally look better than one large one, and they roll into arrangements you did not plan.

For decoration, group by contrast. Three spheres of noticeably different sizes read as a considered arrangement; three of the same size read as a set of samples. In a bowl, fill to just below the rim so the silhouette of the vessel stays visible.

Moss Ball Care

Live Marimo: change the water every one to two weeks, keep the tank cool and out of direct sunlight, and roll them occasionally in your hand under running water to keep the shape even and stop one side flattening. They tolerate neglect better than almost any other aquarium inhabitant.

Decorative spheres: nothing. Never water them — water washes glycerin out of preserved material and leaves it hard. Dust with a cool hairdryer on the lowest setting. Keep them out of direct sun.

Related Collections

For loose material rather than finished spheres, see preserved moss. For bowls and vessels to display decorative spheres in, moss decor.