You may not use black ink to do fur patterns on most islands. …not because it’s associated with ‘black magic’ or anything, it’s just because it’s primarily needed for writing.

Obsidian and igneous rocks come from this island, as well as a variation of the fur thing that does use black ink, and still has some divining practitioners, which gets suspicious regard from visitors.

Wait, igneous rocks on floating islands? That means they have to have left the surface relatively recently…