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Why might M-class asteroids contain nickel-iron metal?

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Illustration showing a massive asteroid above a city map with a dinosaur silhouette for scale, highlighting the asteroid's size compared to major urban areas. — Asteroid This rock would take out more than just a *T. rex*.

M-class asteroids may contain significant amounts of nickel-iron metal because they are believed to be the exposed cores of differentiated asteroids.

During the early history of the solar system, some asteroids were heated to the point where their interiors melted. Because metallic iron is denser than other materials, it sank to the center of these bodies, forming a metallic core while forcing less-dense, basaltic materials toward the surface.1

Over time, violent collisions disrupted these differentiated bodies, stripping away their outer crusts and mantles. This process exposed the dense, nickel-iron cores, which are observed today as M-class asteroids. These asteroids exhibit spectral reflectances similar to iron meteorites, which are also thought to originate from the cores of such parent bodies.213