[Ichneumon]

That's a tile piece from the underside of the wing.

I agree it's probably a tile, but there's no way you can tell if it's "from the underside of the wing" -- such tiles are used on the nose, under the fuselage, and other places as well.

[bonesmccoy]

The nose is RCC.
Leading edge of the wing is RCC
Dark tile that thick is on the underside of the fuselage and the wings... the entire vehicle is a lifting body.

Tragic!