Minecraft wiki entry for Defeating_pyramids, associated text: When attempting to enter the hidden chamber, the player must take care not to step on the pressure plate at the bottom of the pit, as the plate is connected to 9 blocks of TNT just under the hidden chamber's sandstone floor. The pressure plate is situated directly under the blue terracotta. The TNT will cause an explosion sufficient to kill most players (and may even destroy the player's drops), as well as destroy all four of the chests, including their loot.