it's very interesting, sort of like marimo ball algae
that forms a colony that mostly sticks to each other,
rather than spreading and sticking to every surface.
I wonder how it got introduced to your tank.
try to record colony growth and migration rates.
where does it prefer to migrate to? wood, rocks,
substrate, plants, glass, plastic, or any lit surface.
keep us posted with anything you learn.
try to take a tripod closeup for more detail,
and hopefully you can sell some for others
here to experiment with. - good luck