Lavafall Wall

One of the few walls that animates, and one of fewer still that lights the room by itself. Running a strip down the back of a space gives you moving orange light with nothing hanging on the wall, which is why it turns up in forge rooms, volcano builds and anything themed on the underworld.

It is only a background, so none of it is dangerous. You can stand in front of it, build furniture against it and house an NPC in the room without a problem. The joke that never stops being funny is that the item in your hand still burns up if you drop it into real lava.