Screw Attack Blocks are a variety of destructible block that appears in Metroid Fusion and Metroid: Zero Mission. Screw Attack Blocks are destroyed when Samus Screw Attacks through them. Often they look like a solid, normal block. To reveal a Screw Attack Block, Samus must use a Power Bomb or Morph Ball Bomb.
As the Screw Attack appears near the end of both its appearances, Screw Attack Blocks are frequently used to encourage further exploration before the final sequences, protecting many otherwise inaccessible Missile Expansions, Power Bomb Tanks and Energy Tanks.
Official data
Metroid Fusion manual
"Use the Screw Attack to break these blocks apart."
Metroid Zero Mission manual
"Use the Screw Attack to break these blocks apart."