Signs
Navezgane National Park
A stone 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 (2 POIs)
The Wagon Diner (tier 2), Canyon Cliff Dwellings.
Points of interest built with this block (any of its variants), the highest tiers first, from the game's prefab files.