Destructible rocks

From SC2Pod

Destructible Rocks are Doodads that are vulnerable. Rocks have a high amount of health, currently 2000, and have the Armored armor type.

Destroying a group of Destructible Rocks often results in a gateway to a new base or expansion.

In some maps, such as Blistering Sands. Destructible Rocks may also block the construction of a Command Center, Nexus, or Hatchery in a Rich Mineral expansion. This is done to ensure that no player will want to expand there until they can produce a few military units.