Dirt is generally considered an obstacle during mining, though it is nevertheless useful in Survival Mode for quick temporary structures like walk ways, quick easy houses and pillar jumping; it is easily mined even without tools, large quantities are generally readily accessible, and hostile mobs can not generally attack through it. A player caught outside when night approaches, for example, can remain fairly safe by sealing themselves into a small dirt cavity, or pillar-jumping up 16 or 20 blocks. Large dirt structures can even serve as shelter for extended periods, if lit sufficiently to prevent mob spawns. Dirt structures can be outfitted with Doors and any other creature comforts, the same as most other blocks. Players will usually replace the dirt with stronger blocks over time (if only for increased blast resistance) but the dirt serves to block mob lines-of-sight, and to lay out the arrangement of the building. Dirt is also important for its ability to grow a variety of items. Saplings, sugar canes, and mushrooms can be planted directly in dirt (under appropriate conditions for each). Using a hoe on placed Dirt blocks will turn them into Farmland blocks, enabling wheat seeds, pumpkin seeds, melon seeds, potatoes, and carrots to be planted on it. Farmland will revert to dirt unless something is planted on it or it is irrigated by nearby water.