I posted this over in aquarium plants, but It really fits here as well so I figured I'd post for the betta peoples!
Ijust ordered three 5cm marimo from a wholesale company in the UK which I plan to add to my (currently cycling) 5 gallon tank. I plan on adding a betta and a small community of either ghost or cherry shrimps (which I hope he won't eat

).
I have to confess that, as a Japanophile I have always wanted a marimo of my own. Now I will have three! ^_^
I am excited for them to get here, they will be my first additions to the tank, even before my fish get added. Everyone I've talked to online that has them says they are very easy to get attatched to, like having little algea ball pets. I guess because they move around the tank on their own sometimes, like little animals, and sink and float seemingly because they "choose" or "want" to do so. I know they are just plants, but I am very excited. I dare say I...I may name the marimo when they arrive

.
These will also be my first live plants in any fish tank I've ever owned! Hooray! My first tentative steps towards the planted tank I eventually want to maintain some day. I look at the aquascapes with big stones, and drift wood rising gracefully out of underwater fields of javamoss and drool.
And you know as an added bonus they will keep my algea growth down to an almost non existant level, if what I read online about them is correct they are excellent little tank filters and three in a 5 gallon with the help of my shrimp and tank filter should keep the tank sparkling!
I know it's stupid to be so excited over balls of algea, but my first
real hobby tank is coming together (plus I get to own an obscure, living piece of Japanese culture not many people have even heard of) so well I just want to jump for joy and finding these marimo were the icing on my fishy cake!