they are supposedly spores,
there's a mound/island in the middle of an aquarium I need to empty and take down, but it's made from mostly java moss, duckweed, some sort of algae, probably a couple of chain swords that were floating in there,
instead of trying to clean it up, and remove the algae and keep it clean, this happened, and I have to admit to quite liking it.
the picture is through the really dirty glass, from my phone; not sure I trust my phone anywhere else to het a picture you can see, maybe I will take out a bigger camera and see.
if it helps, it's under a Fluval 3.0 light, at maybe half power, for 8 hours a day, with ramping up and down for an hour before and after. (As far as I remember)