I'm about to rescape our shrimp tank (sorry if it's hard to see, ripped up a bunch of crypts and made quite a mess) and for months there's been a mostly self-contained area covered in what looks like really fluffy brown algae.

I let it grow for awhile because it grew very slowly and the shrimp loved to pick around in it, any ideas if it's just a type of algae? It started to spread to another rock recently but otherwise has not spread out of control.

I kind of want to keep a patch of It in the new setup if possible, anyone able to ID it?