Albic's Stone Cube

You think of up to three different unoccupied spaces within range, where up to three 5ft. stone cubes instantly appear. These cubes are non-magical, but still require concentration to maintain, however you do not need to stay within range to maintain concentration. The cubes cannot be moved from their initial location, but can be broken as easily as normal stone. The cubes can support up to 250Lbs each at a time before breaking.