Building blocks
Concrete Destroyed Filler 04
A cobblestone block with 500 hit points.
Harvest drops
Small Stone× 16
Taken apart with a harvesting tool (axe, pickaxe, shovel), before perks and tool bonuses.
When it collapses
Falling, it leaves 
Destroyed Stone (75% of the time) where it lands.
Where to find (10 POIs)
Shamway Factory (tier 5), Hotel Zombona (tier 4), Journey's End (tier 3), Footprint Flats, Hobo Heights Apartments, Jefferson Complex, King's View, Lawless Station, Oops Chemical Company, Table 41.
Points of interest built with this block (any of its variants), the highest tiers first, from the game's prefab files.