I won't buy into an asteroid being an ancient artifact unless I see lots of shredded metal.

I'm not saying I buy your hypothesis, but consider this: if, as you suggest, the objects have been here for millions of years, they may be covered in dust and other natural debris. Even these objects would have a weak gravitational field, so I suspect that would be strong enough to attract enough dust, rocks, etc., to cover the metal.

Consider the case of the loosely aggregated "rock pile" asteroids that are little more than collections of debris flying in formation. I remember reading of simulations a few years ago of what would happen in you detonated a nuke inside one of them. They could come apart, but the gravitational attraction of the debris pieces would be strong enough for them to reaggregate before too long.

Here's an article on Eros where they speculate on the asteroid's characteristics.

This seems to be awash with sediment, forming striking flat "ponds" within craters. It is also strewn with boulders, probably as a result of the recent formation, by impact, of an eight-kilometre- (five mile-) wide crater.

The boulders, like so much of Eros's geomorphology, are a puzzle. It was once believed that the surfaces of asteroids would be clean, as any fragments from an impact would be ejected into space. Data from Near-Shoemaker show the opposite to be true.

The distribution and size of boulders scattered on the asteroid's surface could give scientists a chance to find out what Eros is like below the surface. Simulations of an impact could be carried out to see what parameters (speed, mass of projectile, strength and density of Eros) would yield the observed distribution of boulders.

Beneath the surface Eros may be a loose aggregation of boulders and dust, which would explain how it could absorb the energy of a large impact without breaking apart. Fractures seen on the surface may indicate that Eros has been internally riven by impacts.