Cobweb

Cobweb is a block which slows down movement.

Obtaining
Cobwebs can be obtained by mining them using shears or a sword enchanted with Silk Touch. It will drop 1 piece of string if the shears or sword are not enchanted with Silk Touch, or if water flows over it or a piston pushes it. It will drop nothing when broken using anything else.

In 1.9, Silk Touch is no longer required when using shears, instead cobwebs will always drop itself when broken with shears.

Natural generation
Cobwebs generate naturally in stronghold libraries, igloo basements and abandoned mine shafts.

Usage
Mobs can spawn inside of cobwebs. They will not catch sun fire if they are caught in a cobweb. They also diffuse sky light.

Blocks can be placed on cobwebs, including signs and paintings. When moved by a piston, or sticky piston, the cobweb will drop as a string. When placed in water, it is destroyed and drops a single piece of string. This also happens if water touches them.

Redstone circuits


Cobwebs can be used in redstone as a delay by using a dispenser or dropper to discharge an item into a tower of cobwebs above a pressure plate or hopper.

Effects
All mobs that move through cobwebs will slow down, with the exceptions of spiders and cave spiders. Mobs falling through cobwebs will take 13 seconds to move down by 1 block. They will partially stop blast damage if a player and the TNT/creeper/etc are in the cobweb. The slowing effect of the cobweb will increase if it is placed on ice.

Moving into a cobweb limits the player's movement abilities, as well. When "inside" the cobweb, the player will move at a speed of about 15% of the normal walking speed. Additionally, jumping will vibrate the player akin to jumping in a 2-block-high space. It also slows the time of a player breaking blocks. Like water, cobwebs will prevent players falling into it from taking fall damage, meaning a fatal fall can be mitigated with cobwebs. While traveling down through a cobweb and attacking, it counts towards critical hits the same as jumping and attacking as the player falls.

Items thrown on a cobweb are slowed and will fall through it after about 24 seconds. They will not merge with other items of the same type thrown on the ground.

Cobwebs have different effects on moving entities. A falling block which falls or is shot into a cobweb will slow down and then be destroyed and become a resource after about 4 seconds. The exception is Primed TNT can pass through cobwebs without slowing down if they are shot through fast enough, eventually exploding and destroying the cobweb. A shot arrow will pass through cobwebs without being slowed down.

A minecart with no players in it takes about 9 seconds to fall through a cobweb if a rail is placed directly under the cobweb, but if there is air between the cobweb and the rail, the minecart takes about 34 seconds to fall. Every extra cobweb added will give an additional 25 seconds of falling time. Players are unaffected by cobwebs when in a minecart except when the cobwebs are in the way of the cart.