I wonder if they'll actually find the Nu. I know they let the Sazabi be found in Twilight Axis but in that case it wasn't actually present during the Axis Shock, just Char's eject ball.
I always thought that it carried Chan's soul or emotions or something as when Amuro sees it he says her name, and she was carrying it throughout the movie before trying her hardest to get it to him at the end before dying.
I don’t know what it’s supposed to be, but knowing the Minovsky Particle is a reference to Tomino (Tomino -> Tominosky -> Minovsky), the creator of Gundam franchise, I suspect that it’s shaped like that because T is Tomino’s initial.