There's only so many things you can try with marimo moss balls.
— People cut them apart, flatten the pieces and tie them to rocks/wood, but as stated they don't attach themselves to anything.
— I've seen lots of people flatten them on the substrate in the hopes of them developing into mats but I've never read where it's actually worked.
— If you cut the balls apart, you can roll them into smaller balls and tie them up with cotton thread. They will eventually regrow where cut so you then have mini-balls. Ta-da!
But ... in the single best use of marimo balls I've ever seen, Happy Poet once created this charming shrimp tank:
Happy Poet's yellow shrimp tank
FYI, they should be cleaned every WC. Take them out of the tank (Seriously! Never do this in your tank.) and squeeze them repeatedly while holding them in the used tank water. A disgusting amount of smelly junk will come out. They will refill with water but may look a bit lumpy for a couple of days.
Caution: If you don't clean them regularly, and then you try this, the smell may drive you out of the room. I had some big marimo balls I'd basically ignored for a couple of months in a filled but not inhabited tank. When I tried cleaning them, it was beyond awful. After days of alternately soaking them in fresh water and squeezing them to get the gunk out — and still the smell was horrendous — I decided that whatever had collected in those things did
not need to go into my tank. *sigh* Marimo moss balls are just not for me, even though I do like the look of the furry things. They remind me of tribbles.
