Steel Blocks are a common obstacle introduced in Shovel Knight Pocket Dungeon that the protagonist must clear to progress.
They are scarred and chipped out blocks of raw metal even sturdier than stone, that require much more effort to destroy, specificaly it requires 5 strikes to clear, the highest amount of all the blocks. When playing as Tinker Knight, Steel Blocks provide many more metal scrap bits, necessary to the engineer to activate his mini-mech, compared to the other types of obstacle and as such they appear more commonly, even in Dungeons where they normally do not.