If you haven’t been able to resist the urge to explode Civil 3D objects, or you copied and exploded a surface to extract some contour information, you may not realize that there are monsters lurking in your drawing.
EXPLODE A CIVIL 3D OBJECT- A block is born, usually called *UXXX
EXPLODE THAT BLOCK- AutoCAD entities are born, and your *UXXX block becomes unreferenced in the drawing.
Those blocks- expecially if a corridor, large surface or otherwise, can take up a lot of room in your drawing and they are really useless.
So go ahead and purge those beasts out! Monsters- be gone!