Ghasts are very large, jellyfish or ghost-like mobs that float through the air and shoot fireballs from their mouths. Their bodies are 4 blocks tall and 4 blocks wide with 9 tentacle-like limbs hanging from the bottom. They first appeared in the Halloween Update. Ghasts are able to spawn above any non-transparent block in the Nether, as long as there is sufficient space (at least a 4*4*4 space, with the base centered above a solid block) and the game is not in Peaceful mode.