The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.
The small leaves do look like a java fern, but the long stems with leaves on them seems odd.
If that is java fern you will want to get those roots out of the substrate. They will only rot if buried. Instead consider tying them to a piece of rock or driftwood.