A form of Dwarf Star Matter, it is the only one considered Hyper-Matter.
It resembles a dull grey rock/metal.
As Dwarf Star matter, it is highly dense and only found in the heart of a dying star. It's labeling as 'Hyper-Matter' comes from the fact that it can manipulate gravitons, controlling its own gravity when needed. That an the fact that it can be charged with energy, usually the mystical kind. Uru remains stable by holding a large internal charge. It is normally, nigh indestructible.
However, as dense material, its destruction in its solid state, would result in a nuclear level blast.
- It is based of the material of the same name, from Marvel, the material used to create Thor's Hammer