Marimo moss balls now are rolling into stylish vases and even into tiny orbs and bottles as jewelry.

Consider marimo the moss in your underwater terrarium. Or the floating plant in your aquarium.

Though called moss balls, they are actually algae. And while that sounds like the slime on a rock or aquarium, these balls actually make good houseplants because they don't require much maintenance.

"They don't have a high light requirement. These are northern temperate plants," said Christopher Hardy, associate professor in Millersville University's biology department. "That makes for a plant that works well indoors. And it's neat because it's algae."

What are marimo moss balls?

The name "marimo" comes from Japan, where it means "ball of seaweed." There, the popular moss balls have been turned into a tourist attraction and may be treated like pets, Hardy said. It's kind of like having a pet rock, if it were green and made of algae.

The single alga starts as a filament underwater. Filaments grow toward the light on the water's surface and multiply like beads on a necklace, Hardy said. As the algae grow, waves roll them on the lake bottom, making a round ball.

The nutrients the balls need are in the water, so light is the only other thing they require to thrive.

That Fish Place/That Pet Place has sold the moss balls for six years as part of its selection of live plants for aquariums. The East Hempfield Township company gets its supply from a Florida aqua farm.

A large moss ball there costs $12.99. The store advises not splitting a ball into smaller pieces, but tutorials online show how to do that.

Putting moss to work

"If you have anything that eats algae or plants, they're great," said Justin Hillyard, fish room manager and an aquatic biologist. "A lot of people use them if they have shrimp tanks."

The moss balls serve as food and a mating spot for the shrimp, he said.

"And they look neat," Hillyard said. "It's a big ball floating around in your tank."

But the moss balls aren't just for aquarium and fish fans.

Pinterest has dozens of pictures of marimo floating in organic-shaped vases and glass vessels resembling large light bulbs, sometimes with a little sand and a sea fan.

At the online website Etsy, marimo offerings range from a $109 set of three marimo moss terrariums to decorate a wedding reception to a $3 set of tiny (0.7 centimeter) moss balls.

Marimo throughout the world

Though marimo are now grown commercially, they were first found in large lakes in Japan, Iceland and Scotland.

That poses an interesting question: "If they evolved in Japan, how did they get to Iceland, and how did they get to Scotland?" Hardy asks.

Another mystery involves reports of thousands of marimo appearing on Australian beaches in September, the first time they were found in the Southern Hemisphere.

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