A boulder is a map tile that occurs randomly across the surface of the world, which represent fragments of the substrate stone layer.
[BOULDER] is also the item token for an ordinary large rock (as opposed to a small rock), usually obtained from mining.
Aside from serving no utility whatsoever in fortress mode, they can impede the movement of wagons (but can be walked over by dwarves and other creatures). To remove a boulder, access the designations menu and smooth stone, designate the boulder, and an engraver will turn the boulder into a smooth floor. The resulting floor is the material of the boulder rather than the surrounding material of the ground that the boulder was on.
Alternatively, you can place and then remove a construction on the boulder's tile, which will typically change the tile into a soil floor.
- Boulders covered in "a pile of snow" are not visible unless looked at. However, when viewed from one z-level up, they will appear as . (a period) instead of the · representing open space.
In adventure mode, a boulder provides small rocks of its stone type. These small rocks are useful for knapping to create the tools necessary for butchering.