Bomb Blocks are a type of Destructible Block that is destroyed by Morph Ball Bombs, the Paralyzer, Power Bombs, or the Screw Attack. They appear in Metroid Fusion, Super Metroid, and Metroid: Zero Mission, though in Zero Mission, a shot from the Power Beam will reveal them, while the Wave Beam can reveal clusters of such blocks. They are somewhat replaced in the Prime series by Sandstone and Talloric Alloy, though since the Destructible Blocks' material in the 2D Games is not revealed, it is possible that they are made of one of these materials.
Official Data
Metroid Fusion Manual
"Only Bombs can destroy these special blocks."
Metroid Zero Mission Manual
"Only Bombs can destroy these two special blocks."
Gallery
As seen in Metroid Fusion.
As seen in Metroid: Zero Mission.