Minecraft wiki entry for Blob, associated text: Blobs can generate in caverns or anywhere where there is natural stone and deepslate. Underground deposits of dirt and gravel are generated in this step, followed by the more precious ores: coal, iron, gold, redstone, diamond, emerald (in mountains biomes) and lapis lazuli. They can form only in stone, deepslate, andesite, diorite, granite and tuff. (also in their polished variants, replacing parts of structures), and do not replace each other or any other block. Two or more blobs can form next to each other and appear as a blob made of more than one material.