You ran into a serious Bug, if you have legitly aquired this Block, please report it immidietly/tl

You ran into a serious Bug, if you have legitly aquired this Block, please report it immidietly [sic] is a block that is added by versions 2-4. It is the block used to represent a GregTech TileEntity block that has lost the TileEntity data that would otherwise identify it. It is most commonly created after server-crashing TileEntity errors (such as ClassCastExceptions), and is used as an emergency fallback to prevent further world corruption.

Other than through a server crash or other "serious Bug", there is no way to "legitly aquire this Block".