Building blocks
Metal Spiral Stairs Right
Metal stairs and catwalks are essential for that industrial look.
Harvest drops
Iron× 10
Taken apart with a harvesting tool (axe, pickaxe, shovel), before perks and tool bonuses.
When it collapses
Falling, it leaves 
Scrap Metal Pile (60% of the time) where it lands.
Where to find (2 POIs)
Industrial Tank #2, Leaking Industrial Tank.
Points of interest built with this block (any of its variants), the highest tiers first, from the game's prefab files.