Spider pits are features commonly found within the The Mines. They are easily identified by the sound of clicking spiders and the appearance of a caged room with two levers. One of these levers triggers the spike traps in the floor of the pit, the other lever opens the gates of the pit and releases the spiders into the dungeon.
Sometimes Shelob will spawn in one of these pits, but will be identical to the other spiders in appearance.
Note: Triggering the traps to kill the spiders will give no experience, but if they are shot to death with ranged weapons through the bars of the cage the player will be rewarded with the experience for those kills.