Minecraft wiki entry for Glowstone_blob, associated text: Glowstone blobs consist of one block-wide tendrils extending from a central clump. Being found in caves, hanging above an ocean of lava and even within nether fortresses, they are the main source of charges of glowstone for respawn anchors. They can be found in every nether biome and structure except for Bastions and Ruined Portals.