These cubes are essential puzzle elements. The Weighted Storage Cube is a grey cube used primarily to activate large red buttons or hold down pressure plates. You can pick it up by pressing 'E' and carry it through portals. The Weighted Companion Cube is functionally identical but features pink hearts on its sides and is given a unique, albeit fabricated, personality by GLaDOS. It appears in Test Chamber 17 and serves a specific, memorable purpose. Both cubes are crucial for solving puzzles that require activating mechanisms or blocking laser grids. Learning to transport them efficiently through complex portal setups is a key skill. Remember, you can't fire portals through them, but you can carry them through portals you've already placed.
