Its the second one ive found, its like a little brown capsule shaped like a rectangle, got some hairs comin off of it, bout 7mm long. Might of come off plant but i duno wot one.
Hmm. Well, I bought some bulbs from a dept store here. One of the bulbs would not sink. It turned out to be a dud. That mgiht be true for your tank, but not sure.
Do you have any plants in your tank that came from bulbs, i.e. aponogeton?
Is sounds like the thing I had in a salt water aquarium about a year ago! It was black colored, very small, and looked like had hairs or little spikes coming out of it; and you can see it moving up or down on the side of the glass very slowly! My friend told me it might have been a sea urchin that was stuck to my fish when purchased, but it can't be if you have something like that in a freshwater aquarium