most models of anvils you find are clean anvils, but this is now what they look like when they are in use. a good blacksmith will clean its anvil after use, but during forging, a anvil is often far from clean, especially if the blacksmith is working on a forge weld.
this model is based of a 3d scan of a anvil. for realism, this scan was made while the blacksmith was working. the white paste you can see on the anvil and running down is borax, a white powder that assists in making a forge weld and helps cleaning scale of.
the original scan was very high poly, but by controlled re-topology and baking, this poly count has been brought down significantly without reducing quality. this model is now low poly, ideal for real time rendering and games.