I found a thing in my fish tank (there have been several) that appears to be a pale seed; roughly the size and shape of a popcorn kernel. It is covered in hair in all directions. It's flat, white, and rather frail. It will hold its seed-like structure until a little pressure is applied, and then it starts to crumble.
My fish tank has some gouramis, oscar, and giant danios. There is also some bamboo and dying plants.