“Notion can stick to it without Insignials, but it won’t do anything, and it’ll leak faster. It has also been tested with a lot of other materials, nothing nonmetallic works. Some scholars think it has to do with metal’s simplicity. When you try and use an Insignial to manifest something simple, like oxygen, it’s really easy. But once you get into organic compounds and such things get complicated. So, a theory is that metals work well because they’re simple. Alloys are less sticky, in that theory, as they are less pure. Of course, that has holes too. Elements which are traditionally nonmetallic don’t effect Notion, even if they’re pure. Wait. What’s the ideas realm?”