These 3 destructible model variants are based on the alleged "Stairs in the Woods," where if you find a lone staircase in the middle of the woods, you should never climb up there. According to superstition, one of many bad things can happen if you do. One such example is that you could disappear.
Look up "Stairs in the Woods" in your search engine, and see for yourself.
If on your walk you come across a set of stairs in the woods, then I only pray that you make the right decision and not go up them.
Anyway, I use Blizzard's retail resources from the MPQ. Credits ado to them for the mesh and textures.