When I first pulled it out it looks like a piece of something that ended up sprouting.
My plant stock:
Water Sprite(floating)
Anacharis?
Red Tiger Lotus
Crypt Wendtii "Bronze"
Rangeri Sword
Cabomba Furcata
Ludwigia Repens
Java Moss
Java Fern "Windelov"
Anubias Nana "Petite"
Dwarf Sag
Brazilian Pennywort
and maybe some others but can't think of them.